Work is done whenever a force makes something move. The greater the force and the greater the distance moved, the more work is done.

Transcription

1 MODL Fizik GKAA 4 C Satah condong/nclined plane Sebuah bongkah kayu berjisim m kg diletakkan di atas satah condong yang membuat sudut θ dengan ufuk. Blok kayu dikenakan dengan daya-daya seperti yang disenaraikan di bawah: A block of wood of m kg which is placed on an inclined plane makes an angle θ with the horizontal. he block of wood is acted upon by the forces as listed below: (a) Wx, komponen berat yang selari dengan satah condong. Wx, the weight component which is parallel to the inclined plane. (b) Wy, komponen berat yang berserenjang dengan satah condong. Wy, the weight component which is perpendicular to the inclined plane. (c) tindak balas normal,. the normal reaction,. ngkapkan setiap komponen di (a), (b), (c) dalam sebutan m, g dan θ, di mana g ialah pecutan akibat graviti. Express each of the components in (a), (b), and (c) in terms of m, g and θ, where g is acceleration due to gravity. (a) W x = mg sin θ (b) W y = mg kos θ (c) = W y = mg kos θ θ Wx θ mg Wy.10 MEMAHAM KERJA, EAGA, KASA DA KECEKAPA DERSADG WORK, EERGY, POWER AD EFFCECY Kerja dilakukan apabila daya membuatkan suatu objek bergerak. Semakin besar daya dan jarak sesuatu objek itu digerakkan, maka semakin besar kerja dilakukan. Work is done whenever a force makes something move. he greater the force and the greater the distance moved, the more work is done. Definisi kerja Definition of work Kerja yang dilakukan ialah dikenakan. Work done is force. hasil darab daya yang dikenakan dengan sesaran objek pada arah daya the product of an applied force and the displacement of the object in the direction of the applied Kerja, W = Fs, di mana F = daya, s = sesaran Work, W = Fs, where F = force, s = displacement nit S bagi kerja ialah he S unit of work is the joule, J joule, J Kerja 1 joule dilakukan apabila daya 1 menggerakkan objek sejauh 1 m dalam arah daya dikenakan. 1 joule of work is done when a force of 1 moves an object 1 m in the direction of the force. F s 113 ilam Publication Sdn. Bhd. Fizik g4 BC 015(FSY4p).indd /0/15 :10 PM

2 MODL Fizik GKAA 4 Pengiraan kerja Calculation of work Sesaran, s, bagi objek dalam arah sama dengan daya, F he displacement, s, of the object is in the direction of the force, F Sesaran, s, bagi objek pada arah yang tidak sama dengan arah daya, F he displacement, s, of the object is not in the direction of the force, F s W = Fs F s W = Fs Contoh/Examples 1 Contoh/Examples Seorang budak menolak basikalnya dengan daya 5 melalui jarak 3 m. Kira kerja yang dilakukan oleh budak itu. A boy is pushing his bicycle with a force of 5 through a 5 distance of 3 m. Calculate the work done by the boy. W = Fs = 5 3 m = 75 J (Perhatian/ote: 1 m = 1 J) F F 1 F θ F 1 F = kos θ F 1 = F kos θ W = F 1 s = (F kos θ) s Seorang budak perempuan mengangkat sebuah pasu berjisim 3 kg pada ketinggian 0.4 m. Berapakah kerja yang dilakukan oleh budak perempuan itu? A girl lifts up a 3 kg flower pot steadily to a height of 0.4 m. What is the work done by the girl? W = 3 kg 10 m s 0.4 m = 1 J Atau/Or W = 3 kg 10 kg m = 1 J s 30 Contoh/Examples 3 Seorang pekebun menolak mesin rumput dengan daya 50 pada sudut 60 C dengan ufuk. Berapakah kerja yang dilakukan untuk menolak mesin rumput pada jarak 100 m? A gardener pushes a lawn mower with a force of 50 at an angle of 60 C from horizontal. What is the work done in pushing the lawn mower through a distance of 100 m? F = kos F = 50 kos 60 W = F 100 m = (50 kos 60 ) (100 m) = 500 F ilam Publication Sdn. Bhd. 114 Fizik g4 BC 015(FSY4p).indd /0/15 :10 PM

3 MODL Fizik GKAA 4 iada kerja dilakukan apabila:/o work is done when: Objek berada dalam keadaan pegun. he object is stationary. Arah gerakan objek adalah berserenjang dengan daya yang dikenakan. he direction of motion of the object is perpendicular to that of the applied force. Seorang pelayan membawa dulang makanan dan berjalan. A waiter is carrying a tray of food and walking. Latihan/ Exercises 1 Berapalah kerja dilakukan oleh daya 80 itu? How much work is done by the 80 force? W = m = 40 J F = 80 Sesaran/Displacement = 50 cm Ali menolak sebiji batu dengan mengenakan daya 00. Berapakah kerja yang dilakukannya? Ali pushes a big rock by applying a force of 00. How much work has he done? W = sifar (pegun)/zero (stationary) F = 00 Pegun/Stationary 3 Seorang lelaki menarik satu beban dengan menggunakan satah condong. inggi landasan condong itu ialah 80 cm. Berapakah kerja yang dilakukan oleh lelaki itu untuk menarik beban itu? A man pulls up a load using an inclined plane. he height of the inclined plane is 80 cm. How much work is being done by the man to lift the load? 30 s 80 cm 80 cm = sin 30 s 80 cm s = sin m = sin 30 W = Fs = 30 ( 0.8 m sin 30 ) = 51.0 J F = cm 115 ilam Publication Sdn. Bhd. Fizik g4 BC 015(FSY4p).indd /0/15 :10 PM

4 MODL Fizik GKAA 4 4 Berapakah kerja yang dilakukan oleh Raju untuk mengangkat beban melalui jarak 4 m? How much work is done by Raju to lift the load through the displacement of 4 m? W = m = 600 J F = 150 Sesaran Displacement = 4 m F 5 Satu daya 5 digunakan untuk mengangkat sebuah beg. Encik Rahim berjalan sejauh 0 m dengan memegang beg itu. Berapakah kerja yang dilakukan oleh Encik Rahim terhadap beg itu? erangkan jawapan anda. A force of 5 is used to lift a bag. Encik Rahim walks a distance of 0 m holding the bag. How much work is being done by Encik Rahim with respect to the bag? Explain your answer. Kerja dilakukan adalah sifar kerana daya adalah berserenjang dengan sesaran. Work done is zero because the force is perpendicular to the displacement. F = 5 Sesaran/Displacement = 0 m Menyatakan bahawa apabila kerja dilakukan, tenaga dipindahkan dari satu objek ke satu objek yang lain State that when work is done, energy is transferred from one object to another enaga boleh ditakrifkan sebagai kebolehan untuk melakukan kerja. Energy can be defined as the ability to do work. Satu objek yang boleh melakukan kerja dikatakan mempunyai tenaga. An object that can do work has energy. enaga boleh wujud dalam pelbagai bentuk, misalnya/energy exists in many forms, for example: (a) enaga keupayaan graviti/gravitational potential energy (b) enaga kinetik/kinetic energy (c) enaga keupayaan kenyal/elastic potential energy (d) enaga keupayaan elektrik/electric potential energy (e) enaga bunyi/sound energy (f) enaga mekanik/mechanical energy (g) enaga nuklear/uclear energy Kerja dilakukan apabila daya dikenakan ke atas objek dan objek itu bergerak. ni diikuti dengan pemindahan tenaga dari satu objek ke objek lain. Work is done when a force is applied on an object and the object moves. his is followed by the transference of energy from one object to another. Oleh itu, apabila kerja dilakukan, tenaga dipindahkan dari satu objek ke satu objek yang lain. herefore, when work is done, energy is transferred from one object to another. ilam Publication Sdn. Bhd. 116 Fizik g4 BC 015(FSY4p).indd /0/15 :10 PM

5 MODL Fizik GKAA 4 Definisi tenaga keupayaan graviti/define gravitational potential energy Seorang budak perempuan membuat kerja apabila dia memanjat tangga sebuah papan gelongsor. Dia mempunyai tenaga keupayaan graviti apabila dia berada pada kedudukan tertinggi papan gelongsor itu. A girl does work when she climbs up the stairs of a sliding board. She has gravitational potential energy when she is at the top of the sliding board. enaga keupayaan graviti ialah tenaga yang tersimpan dalam objek disebabkan ketinggian (kedudukan) nya daripada permukaan bumi. he gravitational potential energy is the energy stored in the object because of its height (position) above the earth s surface. enaga keupayaan graviti adalah sama dengan kerja dilakukan untuk menaikkan satu objek kepada satu ketinggian tertentu. Daya diperlukan untuk menaikkan objek adalah sama dengan berat objek, F = mg. he gravitational potential energy is equal to the work done to raise an object to a particular height. he force required to raise the object is the same as the weight of the object, F = mg. Jika jarak menegak yang dilalui oleh objek ialah h, f the distance moved by the object is h, Kerja dilakukan, W = F s = mg h = mgh Work done, W = F s = mg h = mgh Bola Ball Jisim/Mass = m kg enaga keupayaan graviti, Gravitational potential Energy, E P = W h Kedudukan akhir Final position Kedudukan awal nitial position Contoh/Examples Kirakan tenaga keupayaan graviti bagi setiap keadaan berikut. Calculate the gravitational potential energy for each of the following. (a) (b) (c) h Berat Weight m Pendulum Bob m h Kotak Box m h E = mgh E = mgh E = mgh = ( kg) (10 m s ) (0.8 m) = (0.3 kg) (10 m s ) (0. m) = 0.3 kg 10 m s 1. m = 16 J = 0.6 J = 3.6 J 117 ilam Publication Sdn. Bhd. Fizik g4 BC 015(FSY4p).indd /0/15 :10 PM

6 MODL Fizik GKAA 4 ota: otes: A A A 1 enaga keupayaan graviti bagi objek bergantung pada he gravitational potential energy of an object depends on the (a) jisim objek, m mass of the object, m h m B B B (b) kekuatan medan graviti, g gravitational field strength, g (c) perubahan ketinggian, h change in height, h "Kehilangan" tenaga keupayaan graviti tidak bergantung pada kecerunan tetapi bergantung pada jarak tegak ia bergerak. he "loss" of gravitational potential energy does not depend on the gradient of the slope but depends on the vertical distance traversed. Kerja dilakukan sepanjang landasan Work done along this path = 100 J enaga keupayaan graviti 100 J Gravitational potential energy 100 J Kerja dilakukan Work done in this path = mgh = 100 J Definisi tenaga kinetik Definition of kinetic energy Seorang budak lelaki yang sedang mengayuh basikal mempunyai tenaga kinetik. Apabila dia mengayuh lebih pantas, maka dia mempunyai tenaga kinetik yang lebih besar. Pada keadaan pegun, dia tidak mempunyai tenaga kinetik. A boy riding a bicycle possesses kinetic energy. When he rides faster, he will have more kinetic energy. When he is stationary, he does not have any kinetic energy. enaga kinetik ialah tenaga yang diperoleh sesuatu objek disebabkan oleh gerakannya. Kinetic energy is the energy of an object due to its motion. 1 enaga kinetik = mv di mana m = jisim v = halaju Kinetic energy = 1 mv where m = mass v = velocity ilam Publication Sdn. Bhd. 118 Fizik g4 BC 015(FSY4p).indd /0/15 :10 PM

7 MODL Fizik GKAA 4 Contoh/Examples 1 Sebiji bola berjisim 0.5 kg bergerak dengan halaju 4 m s -1. Hitungkan kerja dilakukan. A ball of mass 0.5 kg moves with velocity of 4 m s -1. Calculate the work done. Kerja = enaga kinetik = 1 mv Work done = Kinetic energy = 1 mv = 1 (0.5 kg) (4 m s 1 ) = 4.0 J = 1 (0.5 kg) (4 m s 1 ) = 4.0 J Sebuah kereta berjisim 950 kg bergerak dengan halaju malar 0 m s -1 selama satu minit. Hitungkan kerja yang dilakukan oleh kereta itu dalam tempoh yang tersebut. A car of mass 950 kg moves at a constant velocity of 0 m s -1 for one minute. Calculate the work done by the car during this period. m = 950 kg Kerja dilakukan = enaga kinetik Work done = Kinetic energy = 1 mv = 1 (950 kg) (0 m s 1 ) = J v = 0 m s 1 Menyatakan prinsip keabadian tenaga/state the principle of conservation of energy Prinsip keabadian tenaga menyatakan bahawa tenaga boleh berubah dari satu bentuk ke satu bentuk yang lain, tetapi tidak boleh dicipta atau dimusnahkan. he principle of conservation of energy states that energy can be changed from one form to another form, but it cannot be created or destroyed. Jumlah tenaga di dalam sistem diabadikan he total energy in a system is conserved. Jumlah tenaga sebelum berubah kepada bentuk tenaga yang lain = Jumlah tenaga selepas berubah kepada bentuk tenaga yang lain. otal energy before conversion to other forms of energy = otal energy after conversion to other forms of energy. 119 ilam Publication Sdn. Bhd. Fizik g4 BC 015(FSY4p).indd /0/15 :10 PM

8 MODL Fizik GKAA 4 Aktiviti: Keabadian enaga/activity: Conservation of Energy 1 (a) Sebiji bola dipegang pada ketinggian tertentu di atas lantai. Hold a ball at a certain height above the floor. Apakah jenis tenaga yang terdapat pada bola? What is the energy gained by the ball? enaga keupayaan graviti Gravitational potential energy (b) Bola dilepaskan. Release the ball. (i) Apakah jenis tenaga yang dipunyai oleh bola sejurus sebelum ia menghentam lantai? What is the energy gained by the ball just before it hits the floor? enaga kinetik Kinetic energy Bola Ball Ketinggian Height Lantai/Floor (ii) Dari manakah tenaga pada bola itu berasal? Where does the energy of the ball originate? enaga keupayaan graviti Gravitational potential energy (iii) Apakah hubungan antara tenaga di (a) dengan tenaga di (b)? What is the relationship between the energy in (a) and the energy in (b)? Sama/Equal (a) roli ditolak ke arah dinding untuk memampatkan spring. Push a trolley against a wall to compress a spring. Apakah tenaga yang tersimpan di dalam spring? What is the energy stored in the spring? enaga keupayaan kenyal Elastic potential energy (b) roli dilepaskan supaya ia bergerak menjauhi dinding. Release the trolley so that it moves away from the wall. Apakah yang berlaku kepada tenaga yang tersimpan di dalam spring? What happens to the energy stored in the spring? enaga keupayaan kenyal ditukarkan kepada tenaga kinetik. he elastic potential energy is transferred to kinetic energy. ilam Publication Sdn. Bhd. 10 Fizik g4 BC 015(FSY4p).indd 10 10/0/15 :10 PM

9 MODL Fizik GKAA 4 Contoh/Examples (g = 10 m s ) 1 Sebiji kelapa berjisim 1. kg jatuh dari satu ketinggian. Abaikan rintangan udara. A coconut of mass 1. kg drops from a height. gnore air resistance. (a) (i) entukan jarak buah kelapa itu jatuh dalam masa.0 s. Determine the distance the coconut falls in.0 s. (ii) entukan halajunya, selepas.0 s. Determine its velocity after.0 s. (b) (i) Berapakah jumlah kehilangan tenaga keupayaan graviti selepas.0 s? What is the loss of its gravitational potential energy after.0 s? (ii) Berapakah tenaga kinetiknya?/what is its kinetic energy then? (c) Apakah yang boleh dikatakan tentang kehilangan tenaga keupayaannya dan tenaga kinetik yang diperoleh? What can be said about the loss of its gravitational potential energy and the kinetic energy gained? (a) (i) s = ut + 1 at = (10 m s )(.0 s) = 0.0 m (ii) v = u + gt v = 0 + (10 m s )(.0 s) = 0.0 m s 1 (b) (i) E = mgh = (1. kg) (10 m s ) (0.0 m) = 40 J (ii) enaga kinetik/kinetic energy = 40 J (c) enaga keupayaan graviti yang hilang telah ditukarkan kepada tenaga kinetik. Lost of gravitional potential energy has been changed to kinetic energy. h Sebelum kelapa jatuh Before the coconut falls, enaga keupayaan graviti = mgh Gravitational potential energy = mgh enaga kinetik/kinetic energy = 0 Sebiji durian jatuh dari ketinggian 15 m. Berapakah halaju buah durian itu sejurus sebelum ia menghentam tanah? (Andaikan bahawa g = 10 m s - ) A durian falls from a height of 15 m. What is the velocity of the durian just before it hits the ground? (Assume that g = 10 m s - ) mgh = ½ mv v = gh = 10 m s 15 m v = 17.3 m s 1 3 Sebiji bola dilepaskan pada titik A dari ketinggian 0.8 m dengan menggunakan landasan licin. Berapakah halaju bola itu pada titik B? A ball is released at point A from a height of 0.8 m using a smooth inclined plane. A What is the velocity of the ball at point B? Jumlah tenaga di A = Jumlah tenaga di B 0.8 m otal energy at A = otal energy at B mgh = ½ mv v = gh = 10 m s 0.8 m = 16 m s B v = 4 m s 1 11 ilam Publication Sdn. Bhd. Fizik g4 BC 015(FSY4p).indd 11 10/0/15 :10 PM

10 MODL Fizik GKAA 4 Definisi kuasa Define power Kuasa ditakrifkan sebagai kadar kerja dilakukan atau kadar tenaga ditukarkan. Power is defined as the rate of work done or the rate of energy transformed. Kuasa, P = Kerja Masa = enaga Masa nit S bagi kuasa ialah watt, W atau J s 1. S. unit of power is watt, W or J s 1. Power, P = Work ime Kuasa 1 W dihasilkan apabila 1 J kerja dilakukan dalam masa 1 saat. A power of 1 W is generated when 1 J of work is done in 1 second. = Energy ime Menerangkan kecekapan peralatan Explain what efficiency of a device is Kecekapan = Efficiency = Kuasa output Kuasa input Output power nput power 100% 100% 1 Seorang murid yang berjisim 45 kg mengambil masa 6 s untuk menaiki tangga yang mempunyai 36 anak tangga. Jika tinggi setiap anak tangga ialah 1 cm, kirakan A student of mass 45 kg takes 6 s to climb a flight of stairs that has 36 steps. f each step is 1 cm high, calculate the (a) kerja yang dilakukan oleh murid itu work done by the student (b) kuasa murid itu power of the student KBA Contoh/Examples (a) W = mgh = (45 kg) (10 m s ) (36 anak tangga 0.1 m setiap anak tangga) (45 kg) (10 m s ) (36 steps 0.1 m each step) = J (b) P = J 6 s = 34 W (g = 10 m s ) 1 cm Sebuah motor mengangkat pemberat yang berjisim 1.5 kg pada ketinggian 1.0 m dalam masa 4.0 s. Berapakah kuasa motor itu? A motor lifting a weight having a mass of 1.5 kg up to a height of 1.0 m in 4.0 s. What is the power of the motor? P = mgh t = 1.5 kg 10 m s 1 m 4.0 s = 3.75 W ilam Publication Sdn. Bhd. 1 Fizik g4 BC 015(FSY4p).indd 1 10/0/15 :10 PM

11 MODL Fizik GKAA 4 3 Sebuah enjin petrol mempunyai kuasa output 96 kj per minit. Berapakah kuasa input jika kecekapan enjin itu ialah 0%? A petrol engine has an output power of 96 kj per minute. What is the input power if the engine efficiency is 0%? KBA Kuasa output/output power = J 60 s = W Kuasa output Kecekapan = 100% Kuasa input 0% = W 100% Kuasa input Kuasa input = W 100% 0% = W Output power Efficiency = nput power 100% W 0% = nput power 100% nput power = W 100% 0% = W 1 Sebuah troli dilepaskan dari keadaan rehat pada titik X. Berapakah halaju troli di titik Y? A trolley is released from rest at point X. What is the velocity of the trolley at point Y? KBA Latihan/ Exercises (g = 10 m s ) Dari X ke Y, jarak tegak = 1.5 m From X to Y, the vertical distance = 1.5 m h = 1.5 m X.5 m kg Y 1.0 m mgh = 1 mv Z v = gh = (10 m s )(1.5 m) v = 5.48 m s 1 v B =? Sebiji bola bergerak di sepanjang permukaan mengufuk yang licin dengan halaju 6 m s -1. Bola itu kemudiannya bergerak naik ke atas satu satah condong licin. Ketinggian satah condong itu ialah 1.5 m. Berapakah halaju bola itu di titik B? A ball is moving along a smooth horizontal surface at a velocity of 6 m s -1. he ball then moves up a smooth inclined plane. he height of the inclined plane is 1.5 m. What is its velocity at point B? Jumlah tenaga di A = Jumlah tenaga di B otal energy at A = otal energy at B 1 mv A = mgh + 1 m B 1 (6 m s 1 ) = (10 m s )(1.5 m) + 1 v B 1 v B = (18 15) m s v B =.45 m s 1 KBA A v A = 6 m s 1 B 1.5 m 13 ilam Publication Sdn. Bhd. Fizik g4 BC 015(FSY4p).indd 13 10/0/15 :10 PM

12 MODL Fizik GKAA 4 3 Sebiji bola tenis dilontar ke atas dengan halaju awal 0 m s -1. Berapakah tinggi maksimum yang boleh dicapai oleh bola tersebut? A tennis ball is thrown upwards with an initial velocity 0 m s -1. What is the maximum height that the ball can achieve? ½ mv = mgh, h = v g = (0 m s 1 ) (10 m s ) = 0 m 4 yatakan bentuk tenaga di titik State the form (s) of energy at point (a) P = enaga keupayaan graviti Gravitational potential energy (b) Q = enaga kinetik/kinetic energy (c) R = enaga kinetik + enaga keupayaan graviti Kinetic energy + Gravitational potential energy (d) S = enaga keupayaan graviti Gravitational potential energy P Ketinggian maksimum Maximum height R Q Ketinggian minimum Minimum height Bandul ringkas Simple pendulum S 5 Seorang budak lelaki berjisim, m, sedang berlari menaiki sebuah tangga. Dia mengambil masa, t, untuk sampai ke puncak. Berapakah kuasa budak itu? Beri jawapan anda dalam sebutan m, g, Y dan t. A boy of mass, m. runs up the stairs. He takes time, t, to reach the top. What is the power of the boy? Give your answer in terms of m, g, Y and t. S Kuasa = mgy Power t = mgy t 6 Sebuah kereta dengan kecekapan 5% menghasilkan J tenaga mekanikal setiap saat. Berapakah kuasa output enjin itu? A car engine with an efficiency of 5% produces J of mechanical energy per second. What is the output power of the engine? Kuasa output Kecekapan = 100% Kuasa input Kuasa output 5% = W 100% 5% Kuasa output = 100% W = 750 W Output power Efficiency = nput power 100% Output power 5% = W 100% Output power = 5% 100% W = 750 W ilam Publication Sdn. Bhd. 14 Fizik g4 BC 015(FSY4p).indd 14 10/0/15 :10 PM

13 MODL Fizik GKAA 4 7 Sebuah kren mengangkat beban 500 kg ke ketinggian 1 m dalam masa 8 s. Kuasa input ialah W, berapakah kecekapan motor yang digunakan oleh kren itu? / A crane lifts a load 500 kg to a height of 1 m in 8 s. he power input is W, what is the efficiency of the motor used in the crane? Penyelesaian / Solution: Kecekapan = = Kuasa output Kuasa input 100% 500 kg 10 m s 1 m 8 s W = W W 100% = 16.67% 100% Efficiency = 1 m Output power nput power 100% KBA 8 Seorang budak lelaki berjisim 30 kg sedang duduk di atas puncak satu papan gelongsor condong pada ketinggian.5 m dari tanah. Apabila budak lelaki itu menggelongsor menuruni papan gelongsor, kerja yang dilakukan untuk mengatasi geseran ialah 510 J. Berapakah halaju pelajar itu sejurus sebelum dia menyentuh tanah? / A boy of mass 30 kg sitting on the top end of an inclined sliding board at a height of.5 m from the ground. When the boy slides down the inclined board, the work done to overcome friction is 510 J. What is the velocity of the student just before he touches the ground? Penyelesaian / Solution: mgh = 1 mv J (30 kg)(10 m s )(.5 m) = 1 (30 kg)v J v = 4 m s 1.5 m KBA 9 Abu bersama basikalnya menuruni satu cerun bukit yang mempunyai ketinggian 3 m pada halaju awalnya m s -1 u = m s 1 tanpa mengayuh. Pada kaki bukit, halajunya ialah 6 m s -1. Diberi bahawa jisim Abu dengan basikalnya ialah 75 kg, cari / Abu and his bicycle go down the slope of a hill of 3 m high at an initial velocity of m s -1 v = 6 m s, without pedaling. At the foot of the hill, the velocity 1 is 6 m s -1. Given that the mass of Abu with his bicycle is 75 kg, find 3 m (a) tenaga kinetik awal dipunyai oleh Abu dengan basikal. the initial kinetic energy of Abu and his bicycle. (b) tenaga keupayaan graviti awal yang dipunyai oleh Abu dan basikalnya. the initial gravitational potential energy of Abu and his bicycle. (c) kerja dilakukan menentang geseran sepanjang cerun. the work done against friction along the slope. Penyelesaian / Solution: (a) enaga kinetik/kinetic energy (b) mgh = (75 kg)(10 m s )(3 m) = 1 = 50 J mv (c) enaga di puncak bukit = enaga di kaki bukit = 1 (75 kg)( m Energy at the top of the hill = Energy at the foot of the hill s 1 ) 50 J J = 1 = 150 J (75 kg)(6 m s 1 ) + geseran/friction Geseran/Friction = J 15 ilam Publication Sdn. Bhd. Fizik g4 BC 015(FSY4p).indd 15 10/0/15 :10 PM

14 MODL Fizik GKAA 4 10 Rajah menunjukkan atlit lompat bergalah berjisim 60 kg melompat melepasi palang pada ketinggian 5.0 m. J, K, L, M,, O, P dan Q menunjukkan beberapa peringkat lompatan yang dibuat oleh atlit. Pada titik, ketinggian atlit dari paras palang ialah 0. m he diagram shows a pole vault jumper of mass 60 kg jumping over the bar of height 5.0 m. J, K, L, M,, O, P and Q show the different stages of the jump made by the athlete. At point, the athlete clears the bar with 0. m to spare. KBA Galah Pole O M P J K L ilam getah yang tebal A thick rubber maltress (a) Mengapakah atlit diperlukan untuk memecut kepada halaju tertentu pada peringkat J ke K sebelum dia mula melompat? Why is the athlete required to accelerate from J to K to a certain velocity before he begins to jump? ntuk menambahkan tenaga kinetik. Apabila halaju bertambah, maka tenaga kinetik bertambah. o increase the kinetic energy. Kinetic energy increases with velocity. Q (b) erangkan mengapa galah itu perlu dibengkokkan di L. Explain why the pole has to be bent at L. ntuk mendapatkan tenaga keupayaan kenyal yang maksimum. o get maximum elastic potential energy. (c) Kirakan tenaga keupayaan graviti bagi atlit pada titik. Calculate the gravitational potential energy of the athlete at point. E = mgh = (60 kg) (10 m s ) (5. m) = 3 10 J (d) Berapakah pecutan menegak atlit di peringkat P? What is the vertical acceleration of the athlete at stage P? 10 m s - (e) Mengapa sebuah tilam getah yang tebal diletakkan di kawasan di mana atlit mendarat? Why is a thick rubber mattress placed in the area where the athlete lands? Menambahkan masa hentaman untuk mengurangkan daya impuls. ncrease the time of collision to reduce impulsive force. ilam Publication Sdn. Bhd. 16 Fizik g4 BC 015(FSY4p).indd 16 10/0/15 :10 PM

15 MODL Fizik GKAA 4.11 MEMAHAM KEKEYALA DERSADG ELASCY Aktiviti 1: dea tentang kekenyalan/activity 1: dea of elasticity Definisi kekenyalan Define Elasticity Sifat bahan yang membolehkan objek kembali ke panjang dan bentuk asal apabila daya yang dikenakan ke atasnya dialihkan. A property of matter that enables an object to return to its original length and shape when the force that acts on it is removed. iada daya luar dikenakan. Molekul berada pada kedudukan molekul adalah sifar. asalnya. Daya antara o external force is applied. he molecules are at their original positions. ntermolecular force is equal to zero. Memampatkan pepejal menyebabkan molekulnya bergerak lebih rapat antara satu sama lain. Daya tolakan antara molekul bertindak untuk menolak molekul kembali kepada kedudukan asalnya. Compressing a solid causes its molecules to be moved closer to each other. Repulsive intermolecular forces act to push the molecules back to their original positions. Meregangkan pepejal menyebabkan molekulnya bergerak menjauhi antara satu sama lain. Daya tarikan antara molekul bertindak untuk menarik kembali molekul kepada kedudukan asalnya. Stretching a solid causes its molecules to be moved further from each other. Attractive intermolecular forces act to pull back the molecules to their original positions. Meregang wayar dengan daya luar Stretching a wire by an external force: Molekulnya akan menjauhi antara satu sama lain. ts molecules will move further away from one another. Daya tarikan yang kuat akan bertindak di antara molekul untuk menentang regangan yang dikenakan. Strong attractive forces act between the molecules to oppose the stretching. Apabila daya luar dialih/when the external force is removed: daya tarikan antara molekul membawa molekul kembali ke kedudukan asalnya. the attractive intermolecular forces bring the molecules back to their original positions. Wayar itu kembali ke kedudukan asalnya. he wire returns to its original position. 17 ilam Publication Sdn. Bhd. Fizik g4 BC 015(FSY4p).indd 17 10/0/15 :10 PM

16 MODL Fizik GKAA 4 Aktiviti : Hubungan antara daya dan pemanjangan spring Activity : Relationship between force and extension of a spring ujuan Aim Radas Apparatus Hipotesis Hypothesis Pemboleh ubah dimanipulasi Manipulated variable Pemboleh ubah bergerak balas Responding variable ntuk menyiasat hubungan antara daya dan pemanjangan spring o investigate the relationship between a force and the extension of a spring Spring keluli, lima pemberat berjisim 50 g dan pemegang, pembaris meter, kaki retort Steel spring, five 50 g slotted weights and holder, metre rule, retort stand Pemanjangan spring bertambah dengan penambahan daya Extension of a spring increases as the force increases. Daya/berat/jisim Force/weight/mass Pemanjangan spring Extension of a spring Pemboleh ubah dimalarkan Fixed variable Prosedur Procedure Diameter spring Diameter of the spring 1 andakan kedudukan awal pin pada pembaris meter apabila tiada pemberat dilekatkan kepada spring, l 0. Mark the initial position of the pin on the metre rule when no weight is attached to the spring, l 0. Gantungkan pemberat berjisim 50 g di bahagian hujung spring dan bandingkan kedudukan baru pin sekarang dengan kedudukan asalnya. Attach a slotted weight of 50 g to the end of the spring and compare the new position of the pin with its initial position. 3 kur pemanjangan spring, x = l l 0. Measure the extension of the spring, x = l l 0. 4 langi eksperimen dengan jisim 100 g, 150 g, 00 g dan 50 g. Repeat the experiment with mass 100 g, 150 g, 00 g and 50 g. Spring/Spring Pembaris meter Metre rule Pin/Pin Pemberat Weight Jadualkan data bagi m, F, l dan x. abulate data for m, F, l and x. l 0 = cm Jisim/kg Mass/kg Daya/Force, F F = mg / l / cm Pemanjangan/Extension, x x = l l 0 / cm Merekodkan data Recording data Plotkan graf daya, F melawan pemanjangan spring, x. Plot a graph of force, F against extension of the spring, x. ilam Publication Sdn. Bhd. 18 Fizik g4 BC 015(FSY4p).indd 18 10/0/15 :10 PM

17 MODL Fizik GKAA 4 Daya/Force, F/ Menganalisis data Analysis data Perbincangan Discussion 0 Pemanjangan/Extension, x/cm 1 Daripada graf, apakah hubungan antara daya dengan pemanjangan spring, x? From the graph, what is the relationship between a force and the extension of the spring, x? Daya, F, berkadar langsung dengan pemanjangan spring, x he force, F, is directly proportional to the extension of the spring, x Kira kecerunan graf. unjukkan bagaimana anda mendapat kecerunan daripada graf. Calculate the gradient of the graph. Show how you get the gradient from the graph. Kecerunan = Daya Pemanjangan spring Gradient = Force Extension of spring 3 Langkah berjaga-jaga perlu diambil supaya spring itu tidak diregangkan dengan berat yang berlebihan. erangkan mengapa. Precaution should be taken so that the spring is not stretched by excessive weights. Explain this. Jika spring diregangkan dengan berat yang berlebihan, ia mungkin tidak akan kembali ke panjang asal kerana telah melebihi had kenyal. f the spring is stretched by too large a weight, it might not return to its original length due to its exceeding the elastic limit. yatakan Hukum Hooke State Hooke s Law Graf dayapemanjangan spring Force-extension graph Daya/Force, F/ 0 Pemanjangan/Extension, x/cm Pemanjangan spring berkadar terus dengan daya yang dikenakan asalkan had kenyalnya tidak dilebihi. he extension of a spring is directly proportional to the applied force provided the elastic limit is not exceeded. F = kx di mana/where F = daya ke atas spring / force on the spring x = pemanjangan spring / extension of the spring k = pemalar spring / spring constant Berdasarkan graf/based on the graph: F berkadar terus kepada x. F is directly proportional to x. Kecerunan graf = pemalar spring bagi spring, k. he gradient of the graph = spring constant of the spring, k. Luas di bawah graf adalah sama dengan kerja yang dilakukan untuk memanjangkan spring = tenaga keupayaan elastik Area under the graph is equal to the work done to extend the spring = elastic potential energy Kerja yang dilakukan = tenaga keupayaan kenyal Work done = elastic potiential energy ½ Fx = ½ kx 19 ilam Publication Sdn. Bhd. Fizik g4 BC 015(FSY4p).indd 19 10/0/15 :10 PM

18 MODL Fizik GKAA 4 Had kenyal bagi spring he elastic limit of a spring F/ Had kenyal Elastic limit 0 x (cm) Pemalar daya spring, k Force constant of a spring, k F () Spring keras Stiff spring Spring lembut Soft spring x (m) Berat maksimum yang boleh dikenakan kepada spring supaya spring itu masih boleh kembali ke panjang asalnya apabila daya dialihkan. he maximum weight that can be applied to a spring such that the spring will be able to return to its original length when the force is removed. Jika daya regangan spring melebihi had kenyal, spring tidak kembali ke panjang asal walaupun tiada lagi daya dikenakan ke atasnya. f a force stretches a spring over its elastic limit, the spring cannot return to its original length even though the force no longer acts on it. Hukum Hooke tidak dipatuhi lagi. he Hooke s Law is not obeyed anymore. Pemalar daya spring, k, ialah daya yang diperlukan untuk menghasilkan satu unit pemanjangan spring. he force constant, k, of a spring is the force required to produce one unit of extension spring. k = F unit: m x -1 k ialah pengukuran kekerasan spring./k is a measurement of the stiffness of the spring. of the Spring dengan pemalar daya, k, yang tinggi adalah lebih susah untuk dipanjangkan dan dikatakan lebih keras. he spring with a high force constant, k, is harder to extend and is said to be more stiff. Spring dengan pemalar daya, k, yang kecil adalah lebih mudah untuk dipanjangkan dan dikatakan lebih lembut atau kurang keras. A spring with a small force constant, k, is easier to extend and is said to be softer or less stiff. Faktor-faktor yang mempengaruhi kekenyalan Factors that affect elasticity Faktor Factor Panjang Length Diameter dawai spring Diameter of spring wire Diameter spring Diameter spring Perubahan faktor/change in factor Spring lebih pendek/shorter spring Spring lebih panjang/longer spring Dawai lebih tebal/hicker wire Dawai lebih nipis/hinner wire Diameter lebih kecil/smaller diameter Diameter lebih besar/larger diameter Bagaimana ia mempengaruhi kekenyalan How it affects the elasticity Kurang kenyal/less elastic Lebih kenyal/more elastic Kurang kenyal/less elastic Lebih kenyal/more elastic Kurang kenyal/less elastic Lebih kenyal/more elastic Jenis bahan ype of material Spring diperbuat daripada pelbagai bahan. Perubahan kekenyalan mengikut jenis bahan yang digunakan. Springs are made of different materials. Elasticity changes according to the type of material. ilam Publication Sdn. Bhd. 130 Fizik g4 BC 015(FSY4p).indd /0/15 :10 PM

19 MODL Fizik GKAA 4 Susunan spring yang serupa Arrangement of identical springs Secara bersiri/n series Secara selari/n parallel Spring serupa dentical springs Spring serupa dentical springs Beban Load Beban yang sama dikenakan kepada setiap spring he same load is applied to each spring. egangan dalam setiap spring = ension in each spring = Pemanjangan spring = x Extension of each spring = x Jumlah pemanjangan = x otal extension = x Jika bilangan spring digunakan = n, Jumlah pemanjangan = nx f number of springs used = n, he total extension = nx Beban Load Beban dikongsi bersama sesama spring he load is shared equally among the springs. egangan dalam setiap spring = ension in each spring = Pemanjangan setiap spring = x Extension of each spring = x Jika bilangan spring digunakan = n, f number of springs used = n, Jumlah pemanjangan = n x he total extension = n x Contoh/Examples 1 Panjang asal spring ialah 5 cm. Dengan beban berjisim 0 g, spring memanjang kepada 7 cm. he original length of a spring is 5 cm. With a load of mass 0 g, the length of the spring is extended to 7 cm. entukan/determine (a) pemanjangan spring dengan beban 40 g. the extension of the spring with a load 40 g. (b) panjang spring dengan beban 60 g. the length of the spring with a load of 60 g. (a) 0 g 7 cm 5 cm = cm 40 g 4 cm (b) 0 g menghasilkan pemanjangan cm 0 g gives an extension of cm 60 g pemanjangan/extension 6 cm panjang spring dengan beban 60 g = 5 cm + 6 cm = 11 cm length of spring with 60-g load = 5 cm + 6 cm = 11 cm 131 ilam Publication Sdn. Bhd. Fizik g4 BC 015(FSY4p).indd /0/15 :10 PM

20 MODL Fizik GKAA 4 Contoh/Examples Rajah/Diagram (a) (b) (c) 13.0 cm F = 6.0 F = 1.0 F = 1.0 (a) Panjang asal spring ialah 10.0 cm. Apabila ia diregangkan dengan daya 6, ia memanjang kepada 13.0 cm. Apakah pemalar spring? he original length of a spring is 10.0 cm. When it is stretched by a force of 6, it extends to 13.0 cm. What is the spring constant? x = 13 cm 10 cm = 3 cm k = F x = 6 3 cm = cm 1 (b) Dua spring yang serupa disambungkan secara bersiri seperti ditunjukkan dalam rajah (b). wo identical springs are connected in series as shown in diagram (b). (i) Berapakah jumlah panjang spring jika diregangkan oleh daya 1.0? What is the total length of the spring if stretched by 1.0 force? 6 3 cm Jumlah panjang/otal length 1 6 cm = 10 cm + 10 cm + 6 cm + 6 cm = 3 cm (ii) Berapakah pemalar spring bagi sistem spring di (b)? What is the spring constant of the spring system in (b)? k = F x = 1 1 cm = 1 cm 1 (c) spring yang serupa disambungkan secara selari seperti ditunjukkan dalam rajah (c). identical springs are connected in parallel as shown in diagram (c). (i) Berapakah jumlah panjang sistem spring itu?/what is the total length of the spring system? 4 1 cm Jumlah panjang/otal length 1 3 cm = 10 cm + 3 cm = 13 cm (ii) Berapakah pemalar spring bagi sistem spring di (c)?/what is the spring constant of the spring system in (c)? k = 1 3 cm = 4 cm 1 Contoh/Examples 3 Spring A memanjang cm apabila ia digantung dengan pemberat 10 g. Spring B memanjang 4 cm apabila ia digantung dengan pemberat 10 g. Cari jumlah regangan pada setiap sistem spring seperti ditunjukkan dalam rajah sebelah. KBA Spring A extends by cm when a 10 g weight is hung on it. Spring B extends by 4 cm when a 10 g weight is hung on it. Find the total extension in each of the spring systems shown in the diagrams on the right. (a) A: 10 g cm B: 10 g 4 cm 0 g 4 cm 0 g 8 cm Jumlah pemanjangan/otal extension = 4 cm + 8 cm = 1 cm (b) 10 g 1 cm 50 g 5 cm Pemanjangan sistem/extension in the system = 5 cm (c) Sistem B/System B : 10 g cm 40 g 8 cm A : 10 g cm 40 g 8 cm Pemanjangan sistem/extension in the system = 8 cm + 8 cm = 16 cm 0 g A B A 50 g A B 40 g (a) (b) (c) A B ilam Publication Sdn. Bhd. 13 Fizik g4 BC 015(FSY4p).indd 13 10/0/15 :10 PM

21 MODL Fizik GKAA 4 Contoh/Examples 4 Panjang asal spring ialah 1 cm. Dengan beban 0 g, panjang spring dipanjangkan kepada 15 cm. Berapakah tenaga keupayaan kenyal yang tersimpan di dalam spring? he original length of a spring is 1 cm. With a load of 0 g, the length of the spring is extended to 15 cm. What is the elastic potential energy stored in the spring? E = 1 Fx = 1 (0.0 kg 10 m s ) 0.03 m = J Contoh/Examples 5 Rajah menunjukkan graf daya, F, melawan pemanjangan, x, bagi spring. Berapakah tenaga keupayaan kenyal yang tersimpan apabila spring diregangkan sebanyak 0.4 m? he diagram shows a graph of force, F, against extension, x, for a spring. What is the elastic potential energy stored when the spring is extended by 0.4 m? E = 1 Fx = 1 (0 ) (0.4 m) 0 F/ x/m = 4.0 J Contoh/Examples 6 Rajah menunjukkan sebiji bebola keluli berjisim 10 g ditolak pada penghujung satu spring di sepanjang permukaan licin. Panjang asal spring ialah 14 cm dan pemalar spring ialah 00 m -1. he diagram shows a steel ball of mass 10 g being pushed against one end of a spring along a smooth surface. he original length of the spring is 14 cm and its spring constant is 00 m -1. KBA 14 cm 10 cm entukan/determine (a) tenaga keupayaan kenyal tersimpan di dalam spring./the elastic potential energy stored in the spring. E = 1 kx = 1 (00 m 1 ) (0.04 m) = 0.16 J (b) halaju maksimum bola itu selepas daya mampatan pada spring itu dialihkan. the maximum velocity of the ball after the force of compression on the spring is removed. 1 mv = 0.16 J J v = 0.16 J Perhatian/ote: kg = m kg 0.01 kg (kg m s )(m) = = 3 m s kg v = 5.66 m s 1 = m s Daya Force 133 ilam Publication Sdn. Bhd. Fizik g4 BC 015(FSY4p).indd /0/15 :10 PM

22 MODL Fizik GKAA 4 Latihan/ Exercises Rajah di bawah menunjukkan susunan radas dalam eksperimen untuk menentukan hubungan di antara pemanjangan spring, x, dengan berat, W. Hubungan di antara x dengan W ditunjukkan dalam graf di bawah. he diagram shows the arrangement of an apparatus in an experiment to determine the relationship between the extension, x, of the spring with weight W. he relationship between x and W is shown in the graph below. Pemanjangan, x/cm Extension, x/cm 7 KBA Spring Spring Pemberat berslot Slotted mass (a) (i) yatakan hubungan antara x dan W. State the relationship between x and W. x berkadar langsung dengan W, asalkan had kenyal tidak dilebihi Berat, W/ Weight, W/ x is directly proportional to W, provided the elastic limit is not exceeded. (ii) amakan hukum saintifik yang terlibat dalam hubungan yang dinyatakan di (a)(i). ame the scientific law involved in the relationship stated in (a)(i). Hukum Hooke Hooke s Law (b) andakan dengan tanda pangkah ( ) had kenyal spring di dalam graf. Mark a cross ( ) at the elastic limit of the spring on the graph. (c) Berdasarkan graf, tentukan pemalar daya bagi spring, k (dalam unit m 1 ). Based on the graph, determine the force constant of a spring, k (in m 1 ). k = 10 = 50 m m (d) enaga keupayaan kenyal tersimpan dalam spring apabila ia diregangkan. Kirakan tenaga ini dalam spring apabila ia memanjang sebanyak 4 cm. Elastic potential energy is stored in the spring when it is extended. Calculate this energy in the spring when it is extended by 4 cm. E = 1 Fx = 1 (10 ) (0.04 m) = 0. J ilam Publication Sdn. Bhd. 134 Fizik g4 BC 015(FSY4p).indd /0/15 :10 PM

23 MODL Fizik GKAA 4 Latihan Pengukuhan/ Enrichment Exercises 1 Rajah 1 menunjukkan troli diletakkan di atas landasan terpampas geseran. Diagram 1 shows a trolley placed on a frictioncompensated runway. Rajah 1 / Diagram 1 roli itu akan / he trolley will A bergerak dengan halaju bertambah. move with an increasing velocity. B bergerak dengan halaju berkurang. move with decreasing velocity. C bergerak dengan halaju malar/tetap. move with a constant velocity. D kekal tidak bergerak. remain stationary. angki silinder minyak kereta En. Ali bocor. ompokan minyak kelihatan sepanjang jalan dari A ke B seperti ditunjukkan dalam Rajah. he cylinder oil tank of En. Ali s car is leaking. Lubricant spots are seen along the road from A to B as shown in Diagram. A 10 m 15 m 0 m Rajah / Diagram ni menunjukkan bahawa kereta Ali bergerak dengan t can be concluded that En Ali s car is moving with A pecutan malar. / constant acceleration. B nyahpecutan malar. / constant deceleration. C D pecutan sifar. / zero acceleration. pecutan berkurang dengan malar/tetap. acceleration that is decreasing constantly. 3 Antara pernyataan berikut, yang manakah menghuraikan perlanggaran kenyal antara dua objek dengan betul? / Which of following statements best describes an elastic collision between two objects? A Hanya mementum terabadi sahaja. Only momentum is conserved. B Hanya tenaga kinetik terabadi sahaja. C Only kinetic energy is conserved. Kedua-dua momentum dan tenaga kinetik terabadi. Momentum and kinetic energy are conserved. D Jumlah tenaga, momentum dan tenaga kinetik terabadi. / otal energy, momentum and kinetic energy are conserved. B Rajah 4 menunjukkan graf halaju-masa untuk Adnan, Hamid dan Lim sepanjang perjalanan di jalan lurus mengikut urutan. Diagram 4 shows the velocity-time graphs of Adnan, Hamid and Lim respectively travelling along a straight road. v/m s 1 Adnan v/m s 1 6 t/s v/m s 1 Hamid Lim Rajah / Diagram Jika mereka bertiga memulakan perjalanan dari tempat yang sama dan masa yang sama, susun nama mereka dalam urutan menaik berdasarkan sesaran mereka dari titik permulaan. / f they started their journey from the same place at the same time, arrange their name in accordance to increasing order of their displacements from the starting point. A Adnan, Hamid, Lim B Adnan, Lim, Hamid C Hamid, Lim, Adnan D Lim, Adnan, Hamid 5 Rajah 5 menunjukkan sebiji durian jatuh dari sebatang pokok. Diagram 5 shows a durian falling from a tree. Rajah 5 / Diagram 5 Apakah kuantiti fizik yang ditetapkan semasa durian itu jatuh? / What is the physical quantity that is constant when the durian falls? A Halaju / Velocity B Momentum / Momentum C Pecutan / Acceleration D enaga kinetik / Kinetic energy t/s t/s ilam Publication Sdn. Bhd. Fizik g4 BC 015(FSY4p).indd /0/15 :10 PM

24 MODL Fizik GKAA 4 6 Sebiji bola dilontar ke atas pada ketinggian h m dari tanah. Antara berikut, yang manakah betul tentang gerakan bola itu? A ball is thrown upwards to a height of h m from the ground. Which of the following is true about the motion of the ball? A enaga kinetik adalah malar sepanjang gerakan. B ts kinetic energy is constant throughout the motion. arikan graviti pada ketinggian h adalah sifar. he gravitational attraction at the height h is zero. C Masa yang diambil untuk mencapai ketinggian h meter adalah sama dengan masa yang diambil untuk jatuh dari ketinggian h meter ke tanah. he time taken to reach a height of h metres is the same as the time taken to fall from a height of h metres to the ground. 7 Seorang budak lelaki berjisim 50 kg berada di dalam lif. Berat badannya mencapai 500 apabila A boy of mass 50 kg stands in a lift. His weight reaches 500 when (g = 10 kg 1 ) A lif bergerak ke atas dengan halaju malar. the lift moves upwards with a constant velocity. B lif bergerak ke bawah dengan pecutan seragam. the lift moves downwards with a constant acceleration. C lif itu jatuh bebas. the lift falls freely. 8 Rajah 8 menunjukkan seekor kucing berjisim.5 kg menaiki tangga setinggi 3.0 m dalam masa 1. s. Diagram 8 shows a cat with mass.5 kg running upstairs to a height of 3.0 m in 1. s. 3.0 m B C D Beg udara automatik. Automatic air bag. Roda stereng boleh lipat. Collapsible steering wheels. Cermin kaca tahan air. Shatterproof windscreen glass. 10 Rajah 10 menunjukkan alas bebola, P, yang berjisim 50 g dilepaskan atas satu landasan licin. Diagram 10 shows 50 g ball bearing P, being released on a smooth plane. X Landasan licin Smooth plane Alas bebola P Ball bearing P Rajah 10 Diagram 10 Berapakah halaju alas bebola itu di X? What is the velocity of the ball bearing at X? A 1.60 m s 1 B 4.00 m s 1 C 5.66 m s 1 D 8.00 m s m 11 Suatu beban 800 g digantung pada penghujung spring seperti yang ditunjukkan dalam Rajah 11. Panjang asal spring itu ialah 6.0 cm. A load of 800 g hangs at one end of a spring as shown in Diagram 11. he original length of the spring is 6.0 cm. Rajah 8 / Diagram 8 Berapakah kuasa yang dijanakan oleh kucing itu? How much power is generated by the cat? A B C D 6.3 W 7.5 W 9.0 W 6.5 W 9 Antara berikut, yang manakah bukan ciri-ciri keselamatan yang dipasang pada kenderaan? Which of the following is not a safety feature installed in a vehicle? A Kapasiti enjin. Engine capacity. 800 g 10.0 cm Rajah 11 Diagram 11 enaga keupayaan kenyal yang tersimpan dalam spring ialah he elastic potential energy stored in the spring is A 0.16 J B 1.60 J C J D J ilam Publication Sdn. Bhd. 136 Fizik g4 BC 015(FSY4p).indd /0/15 :10 PM

25 MODL Fizik GKAA 4 1 Rajah 1 menunjukkan seorang lelaki menarik sebuah blok dengan daya 0.0. Diagram 1 shows a man pulling a block with a force of Rajah 13 menunjukkan dua beban yang disambung dengan tali tak kenyal melalui takal licin. Diagram 13 shows two loads connected by an inelastic string through a frictionless pulley. Blok Block G akal licin Frictionless pulley Rajah 1 / Diagram 1 Daya komponen mencancang, G, yang terhasil ialah he vertical component force, G, that is produced is A B C D Soalan Struktur/Structure Questions 4 kg Beban Load 6 kg Beban Load ali tak kenyal nelastic string Rajah 13 / Diagram 13 Pecutan beban 6 kg itu ialah he acceleration of the 6 kg load is A.0 m s C 6.7 m s B 5.0 m s D 0.0 m s 1 Rajah 1.1 menunjukkan sebuah bas yang bergerak dengan halaju 70 km/j dan menunjukkan kedudukan penumpang di dalam bas apabila brek tiba-tiba digunakan. Rajah 1. menunjukkan tukang masak cuba untuk berjabat sos daripada botol. Diagram 1.1 shows a bus moving with a velocity of 70 km/h and shows the condition of a passenger standing in the bus when the brakes are suddenly applied. Diagram 1. shows a cook trying to shake the sauce out of a bottle. Rajah 1.1 / Diagram 1.1 Rajah 1. / Diagram 1. (a) Berdasarkan kedua-dua rajah di atas, nyatakan satu ciri yang dialami oleh penumpang dan sos. Based on both of the diagrams above, state one characteristic experienced by the passengers and the sauce. Penumpang bergerak ke hadapan dan sos cili mengalir keluar daripada botol. he passengers move forward and the chilli sauce comes out from the bottle. (b) Apakah halaju penumpang / What is the velocity of the passenger (i) sebelum pemandu bas membrek? / before the bus driver brakes? 70 km/j / 70 km/h (ii) selepas pemandu bas membrek? / after the bus driver brakes? Halaju yang sama iaitu 70 km/j. / he same velocity that is 70 km/h. (c) Apakah halaju botol apabila sos mengalir keluar? What is the velocity of the bottle when the sauce comes out? Halaju sifar. / Zero velocity. 137 ilam Publication Sdn. Bhd. Fizik g4 BC 015(FSY4p).indd /0/15 :11 PM

26 MODL Fizik GKAA 4 (d) (i) Berdasarkan jawapan (b)(i), tulis satu kenyataan pergerakan bas dan penumpangnya. Based on the answer to (b)(i), write a statement on the motion of the bus and its passengers. Apabila bas brek, halaju bas berkurangan dengan tiba-tiba, penumpang terus bergerak dengan halaju awalnya. When the bus brakes, the velocity of the bus decreases suddenly, the passenger continues to move with its initial velocity. (ii) amakan konsep fizik yang terlibat. / ame the physics concept involved here. nersia / nertia (e) Jika anda dikejar oleh anak gajah, bagaimana anda berlari untuk menyelamatkan diri? erangkan. f you are chased by a baby elephant, how can you run to save yourself? Explain. Saya kena berlari secara zig zag. Anak gajah akan terus bergerak dalam garis lurus apabila saya menukar arah saya dengan tiba-tiba. / have to run in a zig zag manner. he baby elephant will continue to move in a straight line when change my direction suddenly. Satu objek A dengan jisim 40 kg ditarik oleh objek B dengan jisim 80 kg di atas sebuah landasan condong PQ licin seperti yang ditunjukkan dalam Rajah. Kedua-dua takal adalah licin. Object A of mass 40 kg is pulled by object B of mass 80 kg up a frictionless inclined plane, PQ, as shown in Diagram. he pulleys are frictionless. B 80 kg R Q 10 m 8 m Rajah / Diagram θ 40 kg A (a) Hitung kerja yang dilakukan oleh objek B ke atas objek A apabila digerakkan 5 m di sepanjang satah condong PQ. / Calculate the work done by object B on object A when it moves 5 m along the inclined plane, PQ. Kerja / work done = mgh = 40 kg 10 m s 3 m = 1 00 J P (b) Hitung daya paduan apabila objek B menarik objek A. Calculate the resultant force when object B pulls object A. Daya yang bertindak ke atas B / Force acting on B = 80 kg 10 m s = 800 Daya yang bertindak ke atas A / Force acting on A = 40 kg 10 m s sin θ = = 40 Maka, daya paduan / herefore, resultant force = = 560 (c) Hitung pecutan objek B. Calculate the acceleration of object B. Pecutan B = Pecutan A Acceleration of B = Acceleration of A = kg = 4.67 m s ilam Publication Sdn. Bhd. 138 Fizik g4 BC 015(FSY4p).indd /0/15 :11 PM