NATIONAL SENIOR CERTIFICATE GRADE 12

Transcription

1 NTIONL SENIOR ERTIFITE GRE 1 HYSIL SIENES: HYSIS (1) FERURY/MRH 018 MRKS: 150 TIME: 3 hours This question paper consists of 16 pages and 3 data sheets.

2 hysical Sciences/1 E/Feb. Mar. 018 INSTRUTIONS N INFORMTION Write your examination number and centre number in the appropriate spaces on the NSWER OOK. This question paper consists of 11 questions. nswer LL the questions in the NSWER OOK. Start EH question on a NEW page in the NSWER OOK. Number the answers correctly according to the numbering system used in this question paper. Leave ONE line between two subquestions, for example between QUESTION.1 and QUESTION.. You may use a non-programmable calculator. You may use appropriate mathematical instruments. You are advised to use the attached T SHEETS. Show LL formulae and substitutions in LL calculations. Round off your FINL numerical answers to a minimum of TWO decimal places. Give brief motivations, discussions, et cetera where required. Write neatly and legibly.

3 hysical Sciences/1 3 E/Feb. Mar. 018 QUESTION 1: MULTILE-HOIE QUESTIONS Various options are provided as possible answers to the following questions. hoose the answer and write only the letter ( ) next to the question number ( ) in the NSWER OOK, for example constant horizontal force F is applied to a box resting on a horizontal, frictionless surface. Which ONE of the following statements regarding force F is ORRET? Force F will cause the box to move with constant acceleration. constant velocity. constant kinetic energy. constant momentum. () 1. block rests on a table. The table stands on a concrete floor. The normal force is represented by N, as shown in the diagram below. N block table concrete floor Which ONE of the following forces will form an action-reaction pair with the normal force (N)? Force of the block on the Earth Force of the block on the table Force of the table surface on the block Force of the block on the concrete floor ()

4 osition osition osition osition hysical Sciences/1 4 E/Feb. Mar small stone is dropped from a height y above the ground. It strikes the ground after time t, as shown in the diagram below. y ground Take upwards as the positive direction and the ground as zero reference. Ignore the effects of air resistance. Which ONE of the following diagrams shows a correct position-time graph for the motion of the stone? y y 0 time (s) 0 time (s) y y 0 time (s) 0 time (s) ()

5 hysical Sciences/1 5 E/Feb. Mar Learners perform an experiment using identical trolleys, each of mass m. The trolleys are arranged, as shown in the diagram below. They are initially at rest on a frictionless surface and are connected with a compressed, massless spring. ompressed spring mm m m m m When the spring is released it falls vertically down and the single trolley moves with momentum p to the left. The magnitude of the momentum of the two trolleys moving to the right will be: p p 1 p 1 p 4 () 1.5 pendulum bob is released from point above a horizontal surface. t the lowest point, Q, of its swing, it collides with a stationary block situated on a frictionless horizontal surface, as shown below. Ignore air friction. pendulum bob block Q horizontal surface Which ONE of the following combinations of conservation laws can be used to calculate the speed of the bob at Q immediately before and after colliding with the block? SEE T Q onservation of mechanical energy onservation of linear momentum onservation of mechanical energy onservation of linear momentum SEE FTER OLLISION onservation of linear momentum onservation of mechanical energy onservation of mechanical energy onservation of linear momentum ()

6 hysical Sciences/1 6 E/Feb. Mar Which ONE of the statements below about the oppler effect is ORRET? The oppler effect is only applicable to sound waves. The oppler effect can be used to explain the expanding universe. Electrons are ejected from a metal surface by means of the oppler effect. stationary listener hears a lower pitch of the sound from a siren of an approaching vehicle because of the oppler effect. () 1.7 The magnitude of the electrostatic force on a charge Q 1 due to another charge Q is F. oth charges are now doubled without changing the distance between them. The magnitude of the new electrostatic force on Q 1 will be: F F 4F 6F () 1.8 Four identical bulbs,, Q, R and S, are connected to a cell in a circuit, as shown below. The cell has negligible internal resistance. S Q R Which ONE of the following statements about the brightness of bulbs, Q, R and S is ORRET? burns brighter than R. S and Q burn brighter than and R. and R burn brighter than S and Q. LL the bulbs burn with the same brightness. ()

7 hysical Sciences/1 7 E/Feb. Mar Which ONE of the energy conversions below takes place when a motor is in operation? Kinetic to electrical Heat to mechanical Mechanical to electrical Electrical to mechanical () 1.10 In an investigation on the photoelectric effect, the graph of maximum kinetic energy (E k(max) ) versus frequency (f) was obtained for a certain metal, as shown below. Ek(max) (J) Q f (Hz) The intercepts, and Q respectively, represent lanck's constant and threshold frequency. work function and threshold frequency. threshold frequency and work function. threshold frequency and lanck's constant. () [0]

8 Velocity (m s -1 ) hysical Sciences/1 8 E/Feb. Mar. 018 QUESTION (Start on a new page.) Two boxes, and Q, resting on a rough horizontal surface, are connected by a light inextensible string. The boxes have masses 5 kg and kg respectively. constant force F, acting at an angle of 30 o to the horizontal, is applied to the 5 kg box, as shown below. The two boxes now move to the right at a constant speed of m s -1. Q kg F string 30 o m s -1 5 kg Rough surface.1 State Newton's First Law of Motion in words. (). raw a labelled free-body diagram for box Q. (4) ox experiences a constant frictional force of 5 N and box Q a constant frictional force of 3 N..3 alculate the magnitude of force F. (6) The string connecting and Q suddenly breaks after 3 s while force F is still being applied. Learners draw the velocity-time graph for the motion of and Q before and after the string breaks, as shown below. X Z Y 3 7 Time (s).4 Write down the time at which the string breaks. (1).5 Which portion (X, Y or Z) of the graph represents the motion of box Q, after the string breaks? Use the information in the graph to fully support the answer. (4) [17]

9 velocity (m s -1 ) hysical Sciences/1 9 E/Feb. Mar. 018 QUESTION 3 (Start on a new page.) ball is thrown vertically downwards from the top of a building and bounces a few times as it hits the ground. The velocity-time graph below describes the motion of the ball from the time it is thrown, up to a certain time T. Take downwards as the positive direction and the ground as zero reference. The graph is NOT drawn to scale. The effects of air friction are ignored. 9, , 4,955 7,71 8 T time (s) -5 X 3.1 Write down the speed with which the ball is thrown downwards. (1) 3. LL parts of the graph have the same gradient. Give a reason for this. () 3.3 alculate the: Height from which the ball is thrown (3) 3.3. Time (T) shown on the graph (4) 3.4 Write down the: Time that the ball is in contact with the ground at the first bounce (1) 3.4. Time at which the ball reaches its maximum height after the first bounce () Value of X (1) 3.5 Is the collision of the ball with the ground elastic or inelastic? Give a reason for the answer using information in the graph. () [16]

10 hysical Sciences/1 10 E/Feb. Mar. 018 QUESTION 4 (Start on a new page.) The diagram below shows two skateboards, and, initially at rest, with a cat standing on skateboard. The skateboards are in a straight line, one in front of the other and a short distance apart. The surface is flat, frictionless and horizontal. cat surface 4.1 State the principle of conservation of linear momentum in words. () EH skateboard has a mass of 3,5 kg. The cat, of mass,6 kg, jumps from skateboard with a horizontal velocity of 3 m s -1 and lands on skateboard with the same velocity of 3 m s -1. Refer to the diagram below. cat 3 m s -1 surface 4. alculate the velocity of skateboard just after the cat has jumped from it. (5) Immediately after the cat has landed, the cat and skateboard move horizontally to the right at 1,8 m s alculate the magnitude of the impulse on skateboard as a result of the cat's landing. (3) [10]

11 hysical Sciences/1 11 E/Feb. Mar. 018 QUESTION 5 (Start on a new page.) slide, QR, at an amusement park consists of a curved frictionless section, Q, and a section, QR, which is rough, straight and inclined at 30 o to the horizontal. The starting point,, is 3 m above point Q. The straight section, QR, is 5 m long. learner, with mass 50 kg, starting from rest at, slides down section Q, then continues down the straight section, QR. 3 m 5 m Q R 30 o 5.1 State the law of conservation of mechanical energy in words. () 5. alculate the speed of the learner at Q. (4) 5.3 raw a labelled free-body diagram for the learner while he/she is on section QR. (3) The coefficient of kinetic friction (µ k ) between the learner and the surface of section QR is 0, alculate the magnitude of the kinetic frictional force acting on the learner when the learner is on section QR. (3) 5.5 Use energy principles to calculate the speed of the learner at point R. (5) [17]

12 hysical Sciences/1 1 E/Feb. Mar. 018 QUESTION 6 (Start on a new page.) police car is moving at a constant speed on a straight horizontal road. The siren of the car emits sound of constant frequency. EH of two observers, and, standing some distance apart on the same side of the road, records the frequency of the detected sound. Observer records a frequency of 690 Hz and observer records a frequency of 610 Hz. Observer Observer olice car 6.1 State the oppler Effect in words. () 6. In which direction is the car moving? hoose from TOWRS or WY FROM. Give a reason for the answer. () 6.3 etermine the speed of the police car. Take the speed of sound in air as 340 m.s -1. (6) 6.4 Name ONE application of the oppler effect. (1) [11]

13 hysical Sciences/1 13 E/Feb. Mar. 018 QUESTION 7 (Start on a new page.) Two point charges, and S, are placed a distance 0,1 m apart. The charge on is +1,5 x 10-9 and that on S is - x third point charge, R, with an unknown positive charge, is placed 0, m to the right of point charge S, as shown in the diagram below. 0,1 m 0, m + 1,5 x 10-9 S - x 10-9 R 7.1 State oulomb's law in words. () 7. raw a labelled force diagram showing the electrostatic forces acting on R due to and S. () 7.3 alculate the magnitude of the charge on R, if it experiences a net electrostatic force of 1,7 x 10-6 N to the left. Take forces directed to the right as positive. (7) [11] QUESTION 8 (Start on a new page.) is a point 0,5 m from charged sphere. The electric field at is 3 x 10 7 N -1 directed towards. Refer to the diagram below. 0,5 m 8.1 raw the electric field pattern due to charged sphere. Indicate the sign of the charge on the sphere in your diagram. () 8. alculate the magnitude of the charge on sphere. (3) nother charged sphere,, having an excess of 10 5 at point. electrons, is now placed 8.3 alculate the electrostatic force experienced by sphere. (6) [11]

14 urrent I (m) hysical Sciences/1 14 E/Feb. Mar. 018 QUESTION 9 (Start on a new page.) 9.1 The two graphs below show the relationship between current and potential difference for two different conductors, X and Y. Graphs of I versus V for two different conductors, X and Y X Y 0 otential difference (V) State Ohm's law in words. () 9.1. Which ONE of the two conductors, X or Y, is ohmic? Refer to the graph and give a reason for the answer. () 9. In the diagram below, a battery with an emf of 6 V and an internal resistance of Ω, is connected to three resistors, Q and R. voltmeter V is connected across the battery. The ammeter has a negligible resistance. 10 Ω ℇ = 6 V 15 Ω R S V Ω Q 10 Ω 9..1 alculate the ammeter reading when switch S is closed. (5)

15 hysical Sciences/1 15 E/Feb. Mar. 018 The switch S is now open. 9.. Will the ammeter reading in QUESTION 9..1 INRESE, ERESE or REMIN THE SME? Give a reason for the answer. () 9..3 How will the voltmeter reading now compare with the voltmeter reading when the switch is closed? hoose from INRESE, ERESE or REMIN THE SME. (1) 9..4 Explain the answer to QUESTION (3) [15] QUESTION 10 (Start on a new page.) 10.1 Learners want to build a small motor as a project. Write down THREE essential components that are needed for the building of the motor. (3) 10. n electrical device with a resistance of 11 Ω is connected to an source with an rms voltage of 40 V efine the term rms voltage. () 10.. alculate the maximum (peak) current passing through the device. (4) [9]

16 hysical Sciences/1 16 E/Feb. Mar. 018 QUESTION 11 (Start on a new page.) 11.1 In the diagram below, monochromatic light is incident on the metal plate of a photocell. sensitive ammeter shows a reading. Metal plate Monochromatic light How does the energy of the photons of the incident light compare to the work function of the metal plate? hoose from GRETER THN, LESS THN or EQUL TO. Give a reason for the answer. () When a change is made to the monochromatic light, the reading on the ammeter increases. learner makes the following statement with regard to this change: The increase in the ammeter reading is due to an increase in the energy of the incident photons. Give a reason why this statement is INORRET. () What does the photoelectric effect tell us about the nature of light? (1) 11. Ultraviolet radiation is incident on the surface of sodium metal. The threshold frequency (f 0 ) for sodium is 5,73 x Hz. The maximum speed of an electron emitted from the metal surface is 4,19 x10 5 m s efine or explain the term threshold frequency. () alculate the: 11.. Work function of sodium (3) Frequency of the incident photon (3) [13] TOTL: 150

17 hysical Sciences/1 1 E/Feb. Mar. 018 T FOR HYSIL SIENES GRE 1 ER 1 (HYSIS) GEGEWENS VIR FISIESE WETENSKE GR 1 VRESTEL 1 (FISIK) TLE 1: HYSIL ONSTNTS/TEL 1: FISIESE KONSTNTES NME/NM SYMOL/SIMOOL VLUE/WRE cceleration due to gravity Swaartekragversnelling Universal gravitational constant Universele gravitasiekonstant Radius of the Earth Radius van die arde Mass of the Earth Massa van die arde Speed of light in a vacuum Spoed van lig in 'n vakuum lanck's constant lanck se konstante oulomb's constant oulomb se konstante harge on electron Lading op elektron Electron mass Elektronmassa g 9,8 m s - G 6,67 x N m kg R E M E 6,38 x 10 6 m 5,98 x 10 4 kg c 3,0 x 10 8 m s -1 h 6,63 x J s k 9,0 x N m e m e -1,6 x ,11 x kg

18 hysical Sciences/1 E/Feb. Mar. 018 TLE : FORMULE/TEL : FORMULES MOTION/EWEGING v v a t v f f i Δx 1 viδt a t or/of Δy v Δt i 1 a t v i v f v i v f vi a x or/of v f vi a y Δx Δt or/of Δy Δt FORE/KRG F net ma p mv f max s F net Δp = = μ N s Δt = Δp mv f - mv i f k =μ N k w mg m m d m m r 1 1 F =G or/of F=G M M g G or/of g G d r WORK, ENERGY N OWER/REI, ENERGIE EN RYWING W = FΔx cos U mgh or/of E mgh 1 K mv or/of W nc 1 Ek mv K U or/of Wnc Ek Ep W net K or/of Wnet Ek K K f K i or/of Ek Ekf Eki W t ave = Fv ave / gemid = Fv gemid WVES, SOUN N LIGHT/GOLWE, KLNK EN LIG v f 1 T f f v v L L L fs fl fb v v s v vb v v E hf or /of E W o E k(max) or/of E W o Kmax where/waar 1 E hf and/en W0 hf0 and/en Ek(max) mvmax or/of E hc 1 K max mv max

19 hysical Sciences/1 3 E/Feb. Mar. 018 ELETROSTTIS/ELEKTROSTTIK kq Q 1 F E r kq r W V q F E q Q n = e or / of n = Q q e ELETRI IRUITS/ELEKTRIESE STROOMNE R V I Rs R1 R R R R p W = Vq 1 W = VI t W = I R t W = V Δt R emf ( ε ) = I(R + r) emk ( ε ) = I(R + r) q I t W Δt = VI I R V R LTERNTING URRENT/WISSELSTROOM Imax Irms / Vmax Vrms / V I wgk wgk V I maks maks I / gemiddeld V wgk Iwgk ave V rms rms R / R ave I rms Vrms ave / R gemiddeld I wgk gemiddeld V wgk R