M13/4/PHYSI/SPM/ENG/TZ1/XX. Physics Standard level Paper 1. Monday 6 May 2013 (morning) 45 minutes

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1 M13/4/PHYSI/SPM/ENG/TZ1/XX Physics Standard level Paper 1 Monday 6 May 2013 (morning) 45 minutes

2 1. The mass of an elephant is 10 4 kg. The mass of a mouse is 10 2 kg. What is the ratio mass of the elephant? M13/TZ1 A mass of the elephant mass of the mouse? B C C D An archer aims five arrows at the centre of a target. The arrows strike the target as shown below. Which of the following describes the aim of the archer? A. Accurate and precise B. Accurate but not precise C. Precise but not accurate D. Neither accurate nor precise C

3 3. The graph below shows how velocity v varies with time t for a ball thrown vertically upwards from the Earth s surface. The shaded area is equal to the A. displacement. A B. final velocity. C. change in velocity. D. acceleration. M13/TZ1 4. Two identical balls are dropped from a tall building, one a few seconds after the other. Air resistance is not negligible. As the balls fall, the distance between the balls will A. decrease. B. increase. C. increase then remain constant. D. remain constant. C No air resistance y = 5 t 2 when a = 0 time distance y = v t 1 s 5 m 2 s 20 m v is terminal 3 s 45 m speed 4 s 80 m

4 5. Which of the following is always true for an object moving in a straight line at constant speed? A. No forces act on the object. B. No resultant force acts on the object. C. The momentum of the object is zero. D. No work is being done on the object. B M13/TZ1 moving in a straight line at constant speed constant velocity Translational equilibrium: vv is const. aa = 0 FF nnnnnn = 0 6. A person of weight 600 N is standing on a weighing scale in a lift (elevator). The lift is accelerating upwards at 1.0 m s 2. Which of the following is the reading on the scale? A. 0 N B. 540 N C. 600 N D. 660 N D F net = ma F n 600 = 60 F n = 660 N

5 M13/TZ1 7. A spaceship is moving at constant speed in outer space. An internal explosion causes it to break into two pieces that move in opposite directions. Which of the following best describes what happens to its total momentum and total kinetic energy as a result of the explosion? Total momentum Total kinetic energy A. unchanged unchanged B. unchanged increased C. increased unchanged D. increased increased B Momentum is conserved as the system is isolated. Kinetic energy obviously increases as the result of internal explosion.

6 8. A horizontal disc is rotating about a vertical axis through its centre. Points P and Q on the disc are at distances R and 2R respectively from the centre. The acceleration at P is a. Which of the following is the acceleration at Q? A. 0.5a B. a C. 2a D. 4a C PP: aa cc = vv2 rr = aa cc = vv2 RR 2ππππ TT RR M13/TZ1 2 = 4ππ2 RR TT 2 QQ: aa cc = vv2 rr = 2πππππ TT 2RR 2 = 8ππ2 RR TT kg of water at 100 C is mixed with 1.0 kg of water at 0 C in a container insulated from the surroundings. Which of the following is the final temperature of the water? A. 20 C B. 25 C C. 75 C D. 80 C D Thermal energy given by hot water = thermal energy received by cold water m 1 c 1 (100 T) = m 2 c 2 (T 0) c 1 = c (100 T) = 1.0 T T = T

7 10. Which of the following best describes the evaporation of a liquid? M13/TZ1 Location of process Temperature at which process can occur A. at surface at any temperature of liquid B. at surface at maximum liquid temperature only C. throughout liquid at any temperature of liquid D. throughout liquid at maximum liquid temperature only A 11. Which of the following is the temperature of an object related to? A. The kinetic energy of the object B. The random kinetic energy of the particles in the object B C. The potential energy of the particles in the object D. The sum of the random kinetic energy and potential energy of the particles in the object

8 12. The acceleration of an object executing simple harmonic motion is proportional to the A. displacement of the object from equilibrium. B. velocity of the object. C. amplitude of oscillation. D. frequency of oscillation. aa = ωω 2 xx A FF = mmωω 2 xx ωω iiii aaaaaaaaaaaaaa ffffffffffffffffff = 2ππ TT M13/TZ1 Simple Harmonic Motion is periodic motion in which the acceleration/ restoring force is proportional to and in opposite direction of the displacement. 13. A system, consisting of a mass M connected to a spring, oscillates on a frictionless surface with simple harmonic motion between two points, X and Y. Point O is the centre of the oscillation. For the system, at which of the following points is the elastic potential energy equal to the kinetic energy? 1 A. O only KE = mω x0-x 2 B. X and Y only PE = mω x C. O, X and Y 2 D. Neither O, X nor Y D v = ± ω (x 2 0 x 2 ) 1/ ( )

9 M13/TZ1 14. Microwave ovens cause the water molecules in food to resonate. Water molecules have a natural frequency of vibration f. In order to heat the food most effectively, the frequency of the microwaves should have a value A. less than f. B. equal to f. C. greater than f. D. as large as possible. B Natural frequency is the frequency an object will vibrate with after an external disturbance. resonance: The increase in amplitude of oscillation of a system exposed to a periodic driving force with a frequency equal to the natural frequency of the system. If the frequency of a driving force matches the natural frequency of the system, this leads to a better absorption of energy by the system, resulting in large amplitude oscillations.

10 15. Gas particles are equally spaced along a straight line. A sound wave passes through the gas. The positions of the gas particles at one instant are shown below. Which of the distances shown is equal to the wavelength of the wave? M13/TZ1 B Wavelength λ: the distance, measured in the direction of propagation of a wave, between two successive points with the same phase of oscillation. 16. A particle with positive charge +q moves freely from one plate held at potential V 1 to another plate held at potential V 2. Which of the following is the electric potential energy lost by the charge? A. qv 1 B. qv 2 C. q (V 1 +V 2 ) UU = qq VV D. q (V 1 V 2 ) D

11 17. Which of the following graphs shows the relationship between current I and voltage V for a filament lamp? M13/TZ1 RR = VV II by definition Filament does not obey Ohm s law because ratio voltage to current is not constant. We say tungsten is non-ohmic It s resistance increases as current through it increases, because temperature increases. D

12 18. A cell of negligible internal resistance is connected to three identical lamps. A voltmeter is connected across one of the lamps. M13/TZ1 If the filament in lamp X breaks, the reading on the voltmeter will A. become zero. B. decrease. C. stay the same. D. increase. B V = IR R doesn t change Current in the circuit flowing through resistor will be smaller if X breaks, because resistance of the parallel connection will increase, so will total resistance of the circuit, what results in smaller current.

13 M13/TZ1 19. The gravitational field strength at the surface of a certain planet is g. Which of the following is the gravitational field strength at the surface of a planet with twice the radius and twice the mass? A. gg 2 B. g C. 2g D. 4g A Force between planet (mass M) and object of mass m is weight of that object. So mmmm = GG MMMM RR 2 R distance between center of the planet and object m = radius of the planet. gg = GG MM RR 2 gg nnnnnn = GG 2MM (2RR) 2 = gg 2

14 20. Two point charges of size +2q and q are placed as shown below. In which of the regions I, II and III can the resultant electric field strength be zero? M13/TZ1 A. I only B. II only C. III only D. I and III only C In region I electric field due to (+2q) is to the left and electric field due to ( q) is to the right, but one due to (+2q) is always greater then the other one. In region II both electric fields are to the right In region III electric field due to (+2q) is to the right and electric field due to ( q) is to the left, and there is the point at which the are equal in magnitude but in opposite direction resulting in zero resultant electric field.

15 21. A wire is placed in a magnetic field which is directed to the right. The wire carries a current directed into the page. Which of the following is the direction of the force on the wire? M13/TZ1 D R-H-R 1: The direction of the magnetic force on a charge/current is given by the right-hand rule 1 Outstretch fingers in the direction of v (or current I). Curl fingers as if rotating vector v (I ) into vector B. Magnetic force on a positive charge (or I) is in the direction of the thumb Magnetic force on a negative charge points in opposite direction.

16 M13/TZ1 22. Which of the following would decrease the initial activity of a sample of plutonium? A. Placing the sample in a lead container B. Placing the sample in a dark room C. Decreasing the mass of the sample D. Decreasing the temperature of the sample C

17 M13/TZ1 23. A radioactive sample of initial activity 12 Bq has a half-life of 3 days. What is the activity after 6 days? A. 2 Bq B. 3 Bq C. 4 Bq D. 6 Bq B After 3 days activity is half of the initial one = 6 Bq After next 3 days activity is half of that one = 3 Bq 24. The reaction is an example of A. alpha decay. B. artificial transmutation. C. nuclear fusion. D. proton decay. B

18 25. The diagram below shows an energy flow diagram (Sankey diagram) for a car. M13/TZ1 What is the efficiency of the car? A. 30 % B. 40 % C. 70 % A eeeeee = uuuuuuuuuuuu oooooooooooo iiiiiiiiii = 30kkkk 100kkkk D. 100 %

19 26. A small biofuel power station burns ethanol with an overall efficiency of 25 %. The energy density of ethanol is 30 MJ kg 1. The mass of fuel consumed every second is 50 kg. Which of the following gives the useful power output in MW? M13/TZ1 A MMMM = MMMM 1ss oooooooooooo = MMMM kkkk 1 50 kkkk/ss = (30 50) MMMM kkkk 1 kkkk ss = MMMM ss

20 M13/TZ1 27. An oscillating water column ocean-wave energy converter produces power P from waves of a certain amplitude and wavespeed. Which of the following would be the power produced from waves of twice the amplitude and twice the wavespeed? A. 2P B. 4P C. 8P D. 16P C Wave power: P/L amplitude of the wave A, length of wavefront L, ρ - density of water

21 28. The total power radiated by the Sun is P. The distance from the Sun to the Earth is d. The albedo of the Earth is α. What is the power absorbed by each square metre of the Earth s surface? M13/TZ1 αα = tttttttttt rrrrrrrrrrrrrrrrrr ssssssssssssssssss pppppppppp tttttttttt iiiiiiiiiiiiiiii pppppppppp IIIIIIIIIIIIIIIIII: II = PP 4ππdd 2 AAAAAAAAAAAAAAAA bbbbbbbbbbbbbbbbbbb: bb = PP 4ππdd 2 D αα = ssssssssssssssssdd iinnnnnnnnnnnnnnnn tttttttttt iiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiii Intensity scattered = αα (total incident intensity) Intensity absorbed = total incident intensity Intensity scattered = total incident intensity αα (total incident intensity )

22 29. Carbon dioxide is a greenhouse gas because M13/TZ1 A. it absorbs infrared light radiated by the Sun. B. it absorbs ultraviolet light radiated by the Earth. C. its natural frequency molecular oscillation lies in the infrared region. D. its natural frequency molecular oscillation lies in the ultraviolet region. C Short wavelength radiation is received from the sun and causes the surface of the Earth to warm up. The Earth will emit infra-red radiation (longer wavelengths than the radiation coming from the sun because the Earth is cooler than the sun). Some of this infra-red radiation is absorbed by gases in the atmosphere and re-radiated in all directions. Temperature of the Earth s surface will be constant if the rate at which it radiates energy equals the rate at which it absorbs energy. The greenhouse effect is the warming of a planet due its atmosphere allowing in ultraviolet radiation from the Sun, but trapping the infrared radiation emitted by the warm Earth. The greenhouse gas has natural frequency of molecular oscillations in the infrared region, so they easily absorb energy in that region. When the frequency of the electric field is near to the natural frequency of an oscillation of the molecule, the amplitude will be high: The molecule absorbed energy from the field. Infrared radiation drives the vibration of the atoms; visible and UV radiation excites the electron cloud. The greenhouse gases like CO 2 or several organic gases have natural vibration frequency in the infrared domain. They absorb it very strongly. On the other hand, they are transparent for visible and UV light. So the visible and UV light arrives to the surface of the Earth, and is absorbed by metals, rocks, soil, and the leaves of the vegetation and also by waters. The molecules can re-radiate the absorbed energy, but it is more probable, that they collide with other molecules and excite vibrations. These vibrations emit infrared photons which can not go through the atmosphere, as the greenhouse gases absorb them.

23 M13/TZ1 30. Which of the following is most likely to increase the rate of global warming? A. Deforestation B. Increasing the use of nuclear power stations C. Increasing the use of renewable energy sources D. Using natural gas instead of coal for electricity generation A

24 M13/4/PHYSI/SPM/ENG/TZ2/XX Physics Standard level Paper 1 Monday 6 May 2013 (afternoon) 45 minutes

25 1. The length of the side of a cube is 10.0 ±0.3 cm. What is the uncertainty in the volume of the cube? A. ±0.027 cm 3 B. ±2.7 cm 3 C. ±9.0 cm 3 D. ±90 cm 3 D VV VV = aa aa + aa aa + aa aa = 3 aa aa VV = 3aa 2 aa = 90 cccc 3 M13/TZ2 2. Which of the following lists three vector quantities? A. momentum, electric field strength, displacement A B. momentum, displacement, pressure C. pressure, electric current, displacement D. electric current, electric field strength, impulse electric field strength is not a magnitude It is the whole vector

26 3. An object, initially at rest, travels a distance d in a time t at a constant acceleration. What is the time taken for the object to travel 16d from rest at the same acceleration? A. 16t B. 8t C. 4t D. 2t C dd = aa 2 tt2 16dd = aa 2 (4tt)2 4. An object is released above the surface of Earth. Which of the following correctly describes the speed and acceleration before it reaches terminal speed? M13/TZ2 Speed Acceleration A. increases remains constant B. increases decreases C. remains constant remains constant D. remains constant decreases B Air resistance provides a drag force to objects in free fall. The drag force increases as the speed of the falling object increases resulting in decreasing downward acceleration Although acceleration decreases, the speed still increases When the drag force reaches the magnitude of the gravitational force, the falling object will stop accelerating and fall at a constant velocity. This is called the terminal velocity/speed.

27 5. An object of mass m is connected via a frictionless pulley to an object of mass M, where M > m. M rests on a horizontal frictionless surface. FF nnnnnn = mmaa M13/TZ2 What is the acceleration of the system? A T = Ma mg - T = ma mg - Ma = ma a(m+m)=mg

28 6. The graph shows the variation with distance x of the magnitude of the net force F acting on a body initially at rest. M13/TZ2 Which of the following describes how the kinetic energy and the acceleration of the body change with distance? Kinetic energy Acceleration A. decrease decrease B. decrease increase C. increase decrease D. increase increase C 1. KE = W net work done on an object will result in the change of kinetic energy (work is the area under the graph F vs. x) 2. As net F decreases, so does acceleration

29 7. A ball of mass 0.40 kg travels horizontally and strikes a vertical wall with a speed of 5.0 m s 1. It rebounds horizontally with a speed of 3.0 m s 1. The ball is in contact with the wall for a time of 0.20 s. M13/TZ2 What is the average magnitude of the force exerted by the ball on the wall? A N B N C. 4 N D. 16 N D F t = p = p final p initial = m(v final v initial ) we can choose coordinate system (vectors!!!) positive left or positive right as the force is positive we want final direction to be positive, so we choose left to be positive Then F (0.2) = 0.40 [3.0 ( 5.0)] = 3.2 F = 3.2/0.2 = 16 N (positive means to the left)

30 8. A car on a road follows a horizontal circular path at constant speed. Which of the following correctly identifies the origin and the direction of the net force on the car? Origin Direction A. car engine toward centre of circle B. car engine away from centre of circle C. friction between car tyres and road away from centre of circle D. friction between car tyres and road toward centre of circle D M13/TZ2 Newton s first law of motion the law of inertia... objects in motion tend to stay in motion with the same speed and the same direction unless acted upon by a net force. Whatever the object, if it moves in a circle, there is some force acting upon it to cause it to deviate from its straight-line path, accelerate inwards and move along a circular path. For object's moving in circular motion, there is a net force acting towards the center which causes the object to seek the center.

31 9. The temperature of an object is 153 C. Its temperature is raised to 273 C. What is the temperature change of the object? A. 699 K B. 426 K C. 153 K D. 120 K B M13/TZ2

32 10. Two ideal gases X and Y are at the same temperature. The mass of the molecules of gas X is twice the mass of the molecules of gas Y. M13/TZ2 Microscopic level: (absolute) temperature directly proportional to the average kinetic energy of the molecules of a substance: B (KE) avg = 3 2 kkkk k is Boltzmann constant 1 2 mm vv2 aaaaaa ~ TT 1 2 mm xx vv 2 xx aaaaaa 1 2 mm yy vv 2 yy aaaaaa = TT TT vv 2 xx aaaaaa vv 2 yy aaaaaa = mm yy mm xx = 1 2

33 11. A sample contains 4 g of helium and 20 g of neon. The mass number of helium is 4 and the mass number of neon is 20. What is the ratio A. 0.2 B. 1 C. 5 D. 80 B number of atoms of neon number of atoms of helium? Avogadro s number: Number of constituent particles (atoms/molecules) per mole of a given substance is mol 1 M13/TZ2

34 12. Which graph shows how velocity v varies with displacement x of a system moving with simple harmonic motion? A Be aware: Dependence on t: v = ω x 0 sin ωt = v 0 sin ωt M13/TZ2 Dependence on x: v = ± ω x 2 0 x 2 at x = x 0 & x = x 0 v = 0 at x = 0 v = ± ω x 0 D. Is tempting. but D. is sinusoidal, it would show dependence on time not x.

35 13. An object undergoes simple harmonic motion with time period T and amplitude 0.5 m. At time t = 0 s the displacement of the object is a maximum. What is the displacement of the object at time t = 3TT 4? M13/TZ2 A m B m C m Every TT 4 of one amplitude oscillator covers distance D. 0 m D

36 14. Light of wavelength 600 nm travels from air to glass at normal incidence. The refractive index of the glass is 1.5. The speed of light in air is c. Which of the following correctly identifies the speed of the waves and their wavelength in the glass? M13/TZ2 nn = cc vv vv = cc nn = 2cc 3 ffffffffffffffffff ddddddddnn tt ccccccccccc wwwwwww wwwwwwww ccccccccccccc mmmmmmmmmmmm cc = nnnn ffλ aaaaaa = nnnnλ gggggggggg D λ gggggggggg = λ aaaaaa /nn

37 15. Which of the following correctly describes the direction of a ray drawn relative to a wavefront for longitudinal and transverse waves? M13/TZ2 Longitudinal wave Transverse wave A. parallel parallel B. parallel perpendicular C. perpendicular parallel D. perpendicular perpendicular D

38 M13/TZ2 RR = ρρ LL AA = ρρ LL/2 AA nnnnnn AA = 2 AA nnnnnn C rr 2 = 2 rr 2 nnnnnn rr nnnnnn = rr/ 2

39 M13/TZ2 RR TTTTTT = RR + RR 2 = 3 2 RR II = εε RR TTTTTT B

40 18. A proton is accelerated from rest through a potential difference of 1000 V. What is the potential difference through which an alpha particle must be accelerated to gain the same kinetic energy as the accelerated proton? A V B V C. 500 V D. 250 V C UU = qq VV = KKKK qq pppppppppppp VV pppppppppppp = qq aaaaaaaaa VV aaaaaaaaa M13/TZ2 19. The magnitude of the gravitational field strength at the surface of a planet of mass M and radius R is g. What is the magnitude of the gravitational field strength at the surface of a planet of mass 2M and radius 2R? A. gg 4 B. gg 2 C. g D. 2g B Force between planet (mass M) and object of mass m is weight of that object. So mmmm = GG MMMM RR 2 R distance between center of the planet and object m = radius of the planet. gg = GG MM RR 2 gg nnnnnn = GG 2MM (2RR) 2 = gg 2

41 20. Three positive point charges +Q are fixed in position at the vertices of an isosceles triangle. P is the mid point between two of the charges. M13/TZ2 The only electric field that survives at point P is the one due to charge at the right angle corner. The other two cancel each other out. Which arrow correctly identifies the direction of the electric field at point P? A. W B. X C. Y D. Z B

42 21. Three wires, P, Q and R, carry equal currents directed into the plane of the paper. M13/TZ2 Currents in same direction attract! Currents in opposite direction repel! Which arrow correctly identifies the direction of the magnetic force on wire P? A. W B. X C. Y D. Z B

43 22. Which particle is acted on by both the strong nuclear force and the Coulomb force? A. Antineutrino B. Electron C. Neutron D. Proton D M13/TZ2 23. A nucleus of californium (Cf) contains 98 protons and 154 neutrons. Which of the following correctly identifies this nucleus of californium? C

44 24. Which of the following gives the particles of the same energy in an increasing order of ionizing ability? A. β, α, γ B. α, β, γ C. γ, α, β D. γ, β, α D M13/TZ2 25. The use of which energy source enhances the greenhouse effect the most? A. Wood B. Coal C. Wind D. Tidal B

45 26. The volume expansion coefficient of water is γ. The average depth of the ocean is h. What is the expected fractional increase h h increase of Δθ? A. γ Δθ h B. γ Δθ C. γ h Δθ D. γ Δθ B γγ = VV VV 0 θθ in the sea level for a temperature γ-coefficient of volume expansion γγ = θθ increase in temp. coefficient of volume expansion (K 1 or o C 1 ) = change in volume per unit volume per degree lllllllllll wwwwwwwww h (lllllllllll wwwwwwwww h) θθ = h h θθ M13/TZ2

46 27. Which of the following correctly describes the energy transformation within photovoltaic cells and within solar heating panels? M13/TZ2 Photovoltaic cells Solar heating panels A. solar to thermal solar to electrical B. solar to thermal solar to thermal C. solar to electrical solar to electrical D. solar to electrical solar to thermal D

47 28. An oscillating water column (OWC) ocean-wave converter produces a power P. What is the power output of this converter if the amplitude and speed of the waves are both doubled? A. 2P B. 4P C. 8P D. 16P C Wave power: P/L A - amplitude of the wave, L - length of wavefront ρ - density of water M13/TZ2

48 29. The graph shows the spectrum of a black-body. M13/TZ2 Which graph shows the spectrum of a body of emissivity 0.5 at the same temperature as the black-body? (The original graph is shown dotted.) C

49 30. A student states that the following factors may lead to global warming I. decreased albedo of the Earth s surface II. increase in volcanic activity III. deforestation. Which of the above statements are correct? A. I and II only B. II and III only C. I and III only M13/TZ2 D. I, II and III D

50 N13/4/PHYSI/SPM/ENG/NOV/XX Physics Standard level Paper 1 Wednesday 6 November 2013 (morning) 45 minutes

51 1. The sides of a square are measured to be 5.0 ± 0.2 cm. Which of the following gives the area of the square and its uncertainty? A ± 0.2 cm 2 B ± 0.4 cm 2 C. 25 ± 2 cm 2 D. 25 ± 4 cm 2 C aaaaaaaa = aa 2 = 25 cccc 2 (2SSSS) aaaaaaaa aaaaaaaa = aa aa + aa aa = 2 aa aa aaaaaaaa = 2aa aa = cccc 2 =2 cccc 2 Uncertainties are rounded to one digit N13/NOV 2. Which of the following lists two vector quantities and one scalar quantity? A. force, mass, time B. acceleration, energy, momentum C. distance, impulse, power D. density, pressure, temperature B

52 N13/NOV 3. A tennis ball is dropped from the top of a high building. Air resistance cannot be neglected. Which graph represents the variation with time t of the magnitude of the acceleration a of the ball before it hits the ground? B

53 N13/NOV Terminal speed When air resistance is taken into account object in free fall will not accelerate forever. Air resistance depends on the speed of the object. As speed increases, so does air resistance until it reaches the value equal to the weight of the object. At that time net force is zero, so is acceleration. The speed doesn t change any more. It is constant speed.

54 N13/NOV 4. A model plane flies with constant velocity at constant height. Which diagram represents the forces acting on the plane? D Object is in translational equilibrium if F net = 0, a = 0 velocity is const.

55 5. The net force on a body is F. The impulse of F is equal to the A. change in momentum of the body. B. rate of change of momentum of the body. C. change of kinetic energy of the body. D. change of total energy of the body. A N13/NOV Impulse is defined as the product of the net force acting on an object and time interval of action: FΔt vector! (Ns) Impulse F t acting on an object will produce the change of its momentum Δp: F t = p Δp = mv - mu Ns = kg m/s Newton s second law:: Δp F = Δt

56 6. In an inelastic collision A. momentum and kinetic energy are both conserved. B. momentum is conserved but kinetic energy is not. C. kinetic energy is conserved but momentum is not. D. neither momentum nor kinetic energy are conserved. B N13/NOV

57 7. A force which increases uniformly from 0 to a maximum value of F is applied to an object. The object does not move until the force exceeds 0.5F. As the force increases from 0.5F to F the object moves a distance x in the direction of the force. What is the work done by this force? A. 0.25Fx B. 0.5Fx C. 0.75Fx D. Fx C force F 0.5 F N13/NOV distance Work is the area under F vs distance graph x

58 8. A body moves with uniform speed around a circle of radius r. The period of the motion is T. What is the speed of the body? N13/NOV A vvvvvvvvvvvvvvvv iiii tttttttttttttttttttt tttt ttttt cccccccccccc Average velocity is zero, because displacement is zero Speed is constant and is circumference/period

59 9. Molar mass is defined as A. the number of particles in one mole of a substance. B. 1/12 the mass of one atom of carbon-12. C. the mass of one mole of a substance. D. the number of particles in 1/12 of a mole of carbon-12. C N13/NOV 10. Which of the following is true about boiling and evaporation? Boiling Evaporation A. occurs throughout liquid occurs at liquid surface B. occurs throughout liquid occurs throughout liquid C. occurs at liquid surface occurs at liquid surface D. occurs at liquid surface occurs throughout liquid A

60 11. A solid of mass m is initially at temperature ΔT below its melting point. The solid has specific heat capacity c and specific latent heat of fusion L. How much thermal energy must be transferred to the solid in order to melt it completely? A. ml + mc B. mc + mlδt C. mcδt + LΔT D. mcδt + ml D To bring solid to melting point Q = mc T is needed. And then Q = ml is needed to melt it N13/NOV

61 12. For a body undergoing simple harmonic motion the velocity and acceleration are A. always in the same direction. B. always in opposite directions. C. in the same direction for a quarter of the period. D. in the same direction for half the period. D N13/NOV

62 13. Which graph of displacement x against time t represents the motion of a critically damped body? N13/NOV A Critical/heavy damping: occurs if the resistive force is so big that the system returns to its equilibrium position without passing through it. The mass comes to rest at its equilibrium position without oscillating. The friction forces acting are such that they prevent oscillations.

63 14. Which of the following correctly relates the direction of oscillation of the particles in a medium to the direction of energy propagation for transverse and longitudinal waves? Transverse wave Longitudinal wave A. perpendicular perpendicular B. perpendicular parallel C. parallel perpendicular D. parallel parallel B N13/NOV

64 15. Which of the following relates the amplitude A of a travelling wave to the intensity I? C II = PP 4ππdd 2 dd iiii ttttt dddddddddddddddd ffffffff ttttt ssssssssssss oooo pppppppppp aaaaaaaaaaaaaaaa bbbbbbbbbbbbbbbbbbb: bb = EE~AA 2 aaaaaa EE = PP tt LL 4ππdd 2 II~AA 2 N13/NOV 16. Two identical waves of wavelength λ leave two sources in phase. The waves meet and superpose after travelling different distances. Which path difference will result in destructive interference? B

65 17. A resistor X of resistance R is made of wire of length L and cross-sectional area A. Resistor Y is made of the same material but has a length 4L and a cross-sectional area 2A. X and Y are connected in series. What is the total resistance of the combination? A. 1.5R B. 2R C. 3R D. 9R C RR TTTTTT = ρρ LL 4LL + ρρ RR + 2RR AA 2AA N13/NOV

66 N13/NOV 18. A light dependent resistor L is connected in series with a cell C and a fixed resistor R. The cell has a negligible internal resistance. V OUT is the output voltage across L. Which change will increase V OUT? A. Connect another resistor in parallel with L B. Decrease the intensity of light on L C. Increase the resistance of R D. Decrease the emf of C A photoresistor or light-dependent resistor (LDR) or photocell is a light-controlled variable resistor. The resistance of a photoresistor decreases with increasing incident light intensity; in other words, it exhibits photoconductivity. A photoresistor can be applied in light-sensitive detector circuits, and light- and dark-activated switching circuits. VV OOOOOO = II RR LL = B eeeeee RR + RR LL RR LL = eeeeee RR RR LL + 1 If intensity of light decreases, R L increases, and V OUT increases

67 N13/NOV 19. Each of the resistors in the circuit has a resistance of 2.0 Ω. The cell has an emf of 3.0 V and negligible internal resistance. The ammeter has negligible resistance. 1/R TOT = 1/R + 1/3R = 4/3R R TOT = 3/2 Ω I = emf/r TOT = 2 A Current through one resistor I 1 Current through three resistors I 3 What is the ammeter reading? A. 0.4 A B. 0.5 A C. 1.5 A D. 2.0 A C 2 = I 1 + I 3 R I 1 = 3R I 3 I 1 = 3I 3 I 3 = 0.5 A I 1 = 1.5 A

68 N13/NOV 20. Which diagram represents the pattern of electric field lines of two small positive point charges held at the positions shown? B

69 21. The force F between particles in gravitational and electric fields is related to the separation r of the particles by an equation of the form N13/NOV FF = aa bbbb rr 2 Which of the following identifies the units for the quantities a, b and c for a gravitational field? a A. N m 2 C 2 C B. N m 2 C 2 kg C. N m 2 kg 2 C D. N m 2 kg 2 kg b and c D Both A and D will result in the product (abc) = N m 2, but the problem asks about gravitational force, not electric one.

70 22. An electron of mass m e and charge e accelerates between two plates separated by a distance s in a vacuum. The potential difference between the plates is V. N13/NOV dddddddddddddddddddd oooo eeeeeeeeeeeeeeee ffffffffff: EE = FF qq EE = NN/CC What is the acceleration of the electron? EE = VV ss EE = VV mm cccccccccc. EE aa = FF = eeee = ee VV 0 ss = eevv mm ee mm ee mm ee mm ee ss C

71 23. In a particular atom, the nucleon number is the total number of A. protons. B. neutrons. C. electrons. D. protons and neutrons. D N13/NOV 24. For which quantity can the unit MeV c 2 be used? A. Mass A EE = mmcc 2 B. Momentum C. Kinetic energy D. Binding energy mm = EE cc 2 Unit for mass is unit for energy (MeV) divided by c 2

72 25. Uranium-238 forms a nucleus of plutonium-239 as a result of A. electron capture followed by alpha decay. B. electron capture followed by beta decay. C. neutron capture followed by alpha decay. N13/NOV D. neutron capture followed by two beta decays. D 2 protons more means 2 neutrons into 2 protons and two electrons = two beta decays : 0 n p + e 1 0 β + ν That would leave the same number of nucleons, so one extra neutron must be captured

73 N13/NOV 26. In the production of electric power, an advantage of using photovoltaic cells rather than fossil fuels is that the photovoltaic cells A. can be effective in any location. B. can be used continuously. C. have low initial set-up costs. D. are more environmentally friendly when in use. D

74 27. What is the main role of the control rods and the main role of the moderator in a thermal fission reactor? Control Rods Moderator A. decrease neutron speed decrease neutron speed B. decrease neutron speed absorb neutrons C. absorb neutrons decrease neutron speed D. absorb neutrons absorb neutrons C N13/NOV Main energy transformations in a nuclear power station: nuclear energy thermal energy mechanical energy electrical energy Three important components in the design of all nuclear reactors are moderator, control rods and heat exchanger. Moderator is a medium that slows down fast neutrons to make them suitable for reaction (water, graphite, heavy water). Control rods are movable rods that readily absorb neutrons. They can be introduced or removed from reaction chamber in order to control the rate of fission of uranium and plutonium. Made of chemical elements capable of absorbing many neutrons without fissioning themselves (cadmium, hafnium, boron, etc) Heat exchanger is used to seal off the place where nuclear reactions take place from the rest of the environment. In some nuclear power plants, the steam from the reactor goes through a heat exchanger to convert another loop of water to steam, which drives the turbine. The advantage to this design is that the radioactive water/steam never contacts the turbine.

75 28. An oscillating water column (OWC) ocean-wave energy converter uses waves to alter the air pressure in a chamber. Which energy resources must have been involved for this method to generate electricity? I. Tides II. Wind III. Solar A. I only B. II only C. I and II only D. II and III only D It is wave not tide!!!! N13/NOV

76 29. The surface temperature of a black-body emitter is doubled. By what factor does the power emitted by the body increase? A. 32 B. 16 C. 4 D. 2 B PP = σσσσtt 4 iiii aaaaaaaaaaaaaaaaaaaaaaa = llllllllllllllllllll N13/NOV 30. Which option is not a possible solution to reduce the enhanced greenhouse effect? A. Decommission nuclear power plants B. Replace the use of coal and oil with natural gas C. Use combined heating and power systems (CHP) D. Use hybrid motor vehicles A