UNIVRSITY NTRN XMINTION 2017 PHYSIS uration : 2 hours Please read the following instructions carefully. 1. This paper is made up of 50 Multiple-hoice questions and comprises TWNTY (20) printed pages. 2. o not write on the question paper. 3. nswer all questions and indicate your answers on the answer sheet provided. Marks will not be deducted for wrong answers. 4. o not take any paper, including the question paper or unused answer sheets, out of the examination hall. SMPL U 2017 PHY / 02 1
USFUL INFORMTION: cceleration due to gravity, g 9.80 m s 2 vogadro s number, N 6.022 10 23 particles mol Universal gas constant, R 8.314 J K 1 mol 1 Gravitational constant, G 6.673 10 11 N m 2 kg 2 oulomb constant, k 8.99 10 9 N m 2 2 Magnitude of charge of electron, e 1.602 10 19 Mass of electron, m e 9.109 10 31 kg Mass of proton, m p 1.673 10 27 kg Mass of neutron, m n 1.675 10 27 kg Speed of light, c 2.998 10 8 m s 1 Planck s constant, h 6.626 10 34 J s tomic mass unit, u 1.661 10 27 kg SMPL U 2017 PHY / 02 2
Multiple-hoice Questions nswer all questions in this section. 1. What is the SI unit for the average speed of a car? ft yd m m/s m/s 2 2. cyclist accelerates down a hill and then travels at constant speed for a very short time before decelerating, as he climbs up another hill. Which graph possibly shows the variation with time t of the distance s moved by the cyclist? SMPL None of the above U 2017 PHY / 02 3
3. 100 kg cart accelerates at 0.50 m/s 2 west as a horse exerts a force of 60 N west on the cart. What is the magnitude of the force that the cart exerts on the horse? 10 N 50 N 60 N 110 N None of the above 4. In 2001, the leaning tower of Pisa in Italy shown on the right was stabilized by a bundle of steel cables anchored to the ground as shown by the following simplified sketch. If the weight of the tower is W, the tension in the cable is T and the reaction from the ground is R, which vector triangle best represents the forces acting on the tower? SMPL None of the above U 2017 PHY / 02 4
5. Two objects, initially next to each other and at rest, accelerate in the same straight line at different uniform rates. fter 3 s, they are 12 m apart. If they continue to accelerate at the same rate, how far apart will they be 6 s after they started? 18 m 24 m 36 m 48 m 60 m 6. projectile will attain its maximum range if it is fired at an angle of 0 30 45 60 90 from the horizontal. 7. When ball having a projectile motion is rising, it decelerates. it accelerates. it rises up with constant acceleration. its acceleration becomes zero. none of the above SMPL 8. stone is thrown in a vertical plane from a point at the edge of a cliff as shown in the following figure. fter the stone has reached its maximum height, it falls past the cliff edge to the beach. The initial vertical component of the velocity of the stone is 10 ms -1. The time taken between the stone passing the edge of the cliff on its way down and hitting the beach is 1.2 s. U 2017 PHY / 02 5
Ignoring air resistance, what is the height of the cliff measured from the beach? 5.06 m 7.06 m 12.00 m 19.06 m 22.06 m 9. The greatest increase in the inertia of an object would be produced by increasing the mass of the object from 1.0 kg to 2.0 kg net force applied to the object from 1.0 N to 2.0 N time that a net force is applied to the object from 1.0 s to 2.0 s speed of the object from 1.0 m/s to 2.0 m/s none of the above 10. small electric motor is 20% efficient. Its input power is 9.6 W when it is lifting a mass of 0.5 kg at a steady speed v as shown below. What is the value of v? SMPL 0.39 ms -1 2.0 ms -1 2.8 ms -1 3.0 ms -1 3.2 ms -1 11. ball of mass 0.2 kg is attached to an inextensible string of negligible mass and swung in a vertical circle of radius 0.2 m. If its speed at the top of its circular path is 2 ms -1, what is the tension in the string at that moment? 1.96 N 2.04 N 4 N 5.96 N 6 N U 2017 PHY / 02 6
12. car of mass 800 kg decelerates from 22 ms -1 to rest in 12 s. t what average rate must the braking surfaces lose heat if their temperature is not to rise significantly? 16.1 kw 16.5 kw 19.8 kw 21.3 kw 24.2 kw 13. n object is pushed from rest in a horizontal straight line by a variable force F on a rough ground. The ground exerts a constant frictional force of 5 N throughout the motion of the object. The graph of how the variable force F varies with displacement x is shown below. SMPL The magnitude of the kinetic energy of the object when it has travelled 10 m is the area the area + the area + the area + + + the area + + 14. mass is attached to a string and whirled in a vertical circle. The angular velocity of the circular motion is gradually increased. t which point of the motion is the string most likely to break and in which direction will the mass move immediately after the string breaks? U 2017 PHY / 02 7
The string is most likely to break when the mass is at the side where the mass is moving up The mass will move upwards top radially outwards top along the tangent to the circular motion bottom radially outwards bottom 15. Potential energy and kinetic energy are types of electrical energy magnetic energy thermal energy mechanical energy natural energy along the tangent to the circular motion 16. Two identical blocks are released from rest from the tops of two ramps as shown below. SMPL ssuming no friction, what is the ratio of their speeds at the bottom if the ratio of the length is 2, i.e., X 2? Y 1.12 1.86 2.26 3.50 5.52 U 2017 PHY / 02 8
17. The speed of a vehicle of total mass 1.60 x 10 3 kg was brought down to 14.0 ms -1 on a level road by applying brakes. On braking, 550 kj of heat was produced. What is the speed of the vehicle just before the brakes were applied? 40.24 ms -1 29.72 ms -1 26.24 ms - 22.26 ms -1 18.22 ms -1 18. The graph (not drawn to scale) shows the variation with time of the momentum of a ball as it is kicked on a straight line. Initially, the momentum is 5.0 kg ms -1 at time t = 1.0 x 10-3 s. t time t = 3.0 x 10-3 s the momentum is -5.5 kg ms -1. SMPL What is the magnitude of the average force acting on the ball between times t = 1.0 x 10-3 s and t = 3.0 x 10-3 s? 0.25 kn 0.50 kn 3.50 kn 5.25 kn 7.25 kn 19. Two spheres of masses 1 kg and 2 kg, where the 1-kg sphere is moving to the right and 2-kg sphere is moving to the left, are travelling on a smooth horizontal surface with speeds 2 ms -1 and 3 ms -1 respectively on a straight line. They collide head-on elastically, and the respective speeds immediately after their separation are v 1f and v 2f respectively. Which of the following statements is correct for the quantities immediately after the elastic collision? U 2017 PHY / 02 9
Magnitude and direction of v 1 f Magnitude and direction of v 2 f 1 ms -1 to the left 3 2 3 5 3 14 3 ms -1 to the left ms -1 to the right ms -1 to the left 14 ms -1 to the right 3 5 3 2 3 1 3 ms -1 to the left ms -1 to the left ms -1 to the right None of the above None of the above 20. ssuming heat capacity of a 10 g of water to be 42 J K, the heat required to raise its temperature from 25 to 45 would be 84 J 462 J 840 J 4620 J 8400 J 21. sound wave of frequency 400 Hz is travelling in air at a speed of 320 m s. The difference in phase between two points on the wave 0.2 m apart in the direction of travel is π 2 rad π 3 rad π 4 rad π 5 rad π 6 rad SMPL 22. The frequency of the fundamental mode of transverse vibration of a stretched wire 1000 mm long is 256 Hz. When the wire is shortened to 400 mm at the same tension, the fundamental frequency is closest to: 102 Hz 162 Hz 312 Hz 416 Hz 640 Hz U 2017 PHY / 02 10
23. n organ pipe of effective length 0.68 m is closed at one end. Given that the speed of sound in air is 340 m s, the two lowest resonant frequencies are closest to: 125 Hz and 250 Hz 125 Hz and 375 Hz 250 Hz and 500 Hz 250 Hz and 750 Hz 500 Hz and 1000 Hz 24. Two uncharged metal spheres, #1 and #2 are mounted on insulating support rods. third metal sphere #3, carrying a positive charge, is then placed near #1. Now a copper wire is momentarily connected between #1 and #2 and then removed. Finally, sphere #3 is removed. In this final state spheres #1 and #2 are still uncharged. spheres #1 and #2 both carry positive charge. spheres #1 and #2 both carry negative charge. sphere #1 carries positive charge and #2 carries negative charge. sphere #1 carries negative charge and #2 carries positive charge. 25. xperimenter uses a test charge 2q 0 and experimenter uses a very small test charge q 0 to measure an electric field produced by stationary charges. xperimenter finds a field that is greater than the field found by experimenter. less than the field found by experimenter. the same as the field found by experimenter. either greater or less than the field found by experimenter, depending on the amount of charge of the test charges. either greater or less than the field found by experimenter, depending on the masses of the test charges. SMPL 26. Two isolated charges, Q and 2Q, are 2 cm apart. If F is the magnitude of the force acting on charge 2Q, what are the magnitude and direction of the force acting on charge Q? F 2, toward 2Q. 2F, away from 2Q. F, toward 2Q. F, away from 2Q. 2F, toward 2Q. U 2017 PHY / 02 11
27. hollow metal sphere of radius R is positively charged. Of the following distances from the center of the sphere, which location will have the greatest electric field strength? 0. R 2. R. 2R. None of the above because the field is of constant strength. 28. point charge Q = 900 10 9 and two unknown point charges, q 1 and q 2, are placed as shown. The electric field at the origin O, due to charges Q, q 1 and q 2 is equal to zero. The unknown point charge q 1 is closest to +55 10 9. +95 10 9. 95 10 9. +140 10 9. 140 10 9. SMPL 29. Two conducting spheres of different radii each has charge Q. Which of the following occurs when the two spheres are connected with a conducting wire? No charge flows. Negative charge flows from the larger sphere to the smaller sphere until the electric field at the surface of each sphere is the same. Negative charge flows from the larger sphere to the smaller sphere until the electric potential of each sphere is the same. Negative charge flows from the smaller sphere to the larger sphere until the electric field at the surface of each sphere is the same. Negative charge flows from the smaller sphere to the larger sphere until the electric potential of each sphere is the same. U 2017 PHY / 02 12
30. capacitor of capacitance is charged to a potential difference of V while a second capacitor of capacitance 2 is charged to a potential difference of 2V. combined capacitor is then formed by connecting the two positive plates together and the two negative plates together. What happens to this system of capacitors? oth charge and energy increase. oth charge and energy decrease. oth charge and energy remain constant. nergy decreases but charge remains constant. harge increases but energy remains constant. 31. Two point charges, +4.0 μ and 4.0 μ are placed as shown in the diagram. n additional charge of +2.0 μ is placed at point. The electric potential energy of this system of charges is closest to: 486 10 3 J 455 10 3 J 264 10 3 J +264 10 3 J +486 10 3 J SMPL U 2017 PHY / 02 13
32. In the circuit shown, the emf of the battery is ε = 10.0 V and each of the seven capacitors has capacitance = 10.0 μ. The charge on capacitor 1 is closest to: 20.0 μ 40.0 μ 50.0 μ 60.0 μ 100.0 μ 33. The ideal battery in the figure shown below has emf ε = 6.0 V. Plot 1 in the figure above gives the electric potential difference V that can appear across resistor R 1 of the circuit versus the current I in that resistor. The scale of the V axis is set by V s = 18.0 V and the scale of the I axis is set by I s = 3.00 m. Plots 2 and 3 are similar plots for resistors R 2 and R 3 respectively. The current in resistor R 1 is closest to: SMPL 0.55 m. 0.82 m. 1.36 m. 4.0 m. 6.0 m. U 2017 PHY / 02 14
34. Given that ε 1 = 10 V, ε 2 = 20 V, R 1 = 10 Ω, R 2 = 20 Ω and R 3 = 40 Ω, the power delivered by the battery ε 1 is closest to: 2.5 W. 5.0 W. 10.0 W. 12.5 W. 20.0 W. 35. velocity selector has an electric field of magnitude 2470 N directed vertically upward and a horizontal magnetic field. Positively charged particles, travelling east at a speed of 6.50 10 3 m s, enter the velocity selector and are able to pass completely through without being deflected. When a different particle with an electric charge of 4.00 10 12 enters the velocity selector travelling east, the net force acting on it is 1.90 10 9 N pointing directly upward. The speed of this particle is closest to: 2750 m s 5250 m s 7750 m s 8750 m s 9250 m s SMPL 36. small coil lies inside a large coil. The two coils are horizontal and concentric as shown. The large coil carries a constant clockwise current. The smaller coil is pulled perpendicular out of the plane of the paper. Which of the following describes the direction of the induced current in the smaller coil and the resultant force between the coils? counter-clockwise, attraction. clockwise, attraction. counter-clockwise, repulsion. clockwise, repulsion. no induced current, no force. U 2017 PHY / 02 15
37. The circuit shown is in a uniform magnetic field that is into the page and is decreasing in magnitude at a rate of 150 T s. etermine the reading on the ammeter and the direction of current flowing through the ammeter. 0.35, downward. 0.35, upward. 0.50, upward. 0.65, upward. 0.65, downward. 38. steady current I dissipates a certain power in a variable resistor. The resistance is remained to obtain the same power when a sinusoidal alternating current is used. What is the r.m.s. value of the alternating current? I 2 I 2 I 2 I 2I SMPL 39. capacitor is connected in series to an ideal a.c. power supply. The voltage across the capacitor lags the current in the capacitor by 90. leads the current in the capacitor by 90. is in phase with the current in the capacitor. leads the current in the capacitor by 45. lags the current in the capacitor by 45. U 2017 PHY / 02 16
40. The wavelength of light in water is 788 nm. If the refractive index for this light in water is 1.33, the speed of this light in water is closest to: 2.95 10 8 m s 1 1.95 10 8 m s 1 1.25 10 8 m s 1 2.25 10 8 m s 1 2.50 10 8 m s 1 41. ray of light propagates in water (n = 1.333) and strikes a sheet of glass (n = 1.523). If the angle of refraction in the glass is 35.2, the angle of incidence is closest to: 30.3 32.8 35.2 41.2 48.8 42. Two thin lenses are placed 5 cm apart along the same axis and illuminated with a beam of light parallel to that axis. The first lens in the path of the beam is a diverging lens of focal length 10 cm whereas the second is a converging lens of focal length 5 cm. If the second lens is now moved towards the first, the emergent light changes from parallel to divergent changes from divergent to parallel changes from parallel to convergent changes from convergent to parallel changes from convergent to divergent SMPL 43. Two identical light waves, and, are emitted from different sources and meet at a point P. The distance from the source of to the point P is L ; and the source of is a distance L from P. Which one of the following statements is necessarily true concerning the interference of the two waves? and will interfere constructively because their amplitudes are the same. and will interfere destructively if L = L. and will interfere destructively if L L = (m + 1 2)λ where m = 0,1,2,3, and will interfere destructively if L is not equal to L. and will interfere constructively because their wavelengths are the same. U 2017 PHY / 02 17
44. iffraction occurs when light passes through a single slit. Rank the following three choices in decreasing order, according to the extent of the diffraction that occurs (largest diffraction first): I blue light, wide slit II red light, narrow slit III red light, wide slit Note: The blue light referred to in choices I and III is the same wavelength. lso, the narrow slit referred to in choices I and II is the same width. I, II, III II, I, III II, III, I I, III, II III, II, I 45. grating spectrometer is used to view the spectrum of light from a helium discharge tube. The three brightest spectral lines seen are blue, red and yellow in colour. These lines appear at the positions labeled, and in the figure below though not necessarily in that order of colour. In this spectrometer, the distance between the grating and screen is 30 cm and the slit spacing in the grating is 1870 nm. The wavelength of the red colour spectral line is closest to: 398 nm 454 nm 565 nm 669 nm 767 nm SMPL 46. rrange the following electromagnetic waves in order of increasing energy: visible light, X-rays, microwaves, infra-red and ultra-violet. X-rays, ultra-violet, visible light, infra-red and microwaves. X-rays, infra-red, visible light, ultra-violet and microwaves. Visible light, infra-red, ultra-violet, microwaves and X-rays. Microwaves, infra-red, visible light, ultra-violet and X-rays. Microwaves, ultra-violet, infra-red, X-rays and visible light. U 2017 PHY / 02 18
47. lectrons are emitted from a certain metal with a maximum kinetic energy of 2 ev when 6-eV photons are incident on its surface. If photons of half the wavelength are incident on this metal which one of the following statements is true? No electrons will be emitted. lectrons will be emitted with a maximum kinetic energy of 2 ev. lectrons will be emitted with a maximum kinetic energy of 4 ev. lectrons will be emitted with a maximum kinetic energy of 8 ev. lectrons will be emitted with a maximum kinetic energy of 12 ev. 48. The de roglie wavelength of an electron is 1.2 10 10 m. The magnitude of momentum of the electron is closest to: 5.9 10 25 kg m s 1 1.8 10 24 kg m s 1 5.6 10 24 kg m s 1 1.7 10 23 kg m s 1 5.2 10 23 kg m s 1 49. stronomers observe a series of spectral lines in the light from a distant galaxy. On the hypothesis that the lines form the Lyman series for an (new?) unknown atom, they start to construct the energy-level diagram shown, which gives the wavelengths of the first four lines and the short-wavelength limit of this series. SMPL The energy of the ground state is closest to: 8.18 ev 6.14 ev 0 ev +6.14 ev +8.18 ev U 2017 PHY / 02 19
50. The radioactive isotope radon-222 ( 86Rn) may decay spontaneously by emitting an alpha particle. The daughter nucleus is an isotope of polonium (Po). The atomic masses of these isotopes are: 222 Rn 222, 222.0157 u; Po, 218.00896 u; He, 4.00260 u; sample of radon-222 contains 3.0 10 7 nuclei. The total energy that will be release in a time interval of 3T 1 2 through alpha decay of the radon-222 is closest to: 3.856 MeV 5.785 10 7 MeV 8.677 10 7 MeV 1.012 10 8 MeV 1.085 10 8 MeV 4 N OF PPR SMPL U 2017 PHY / 02 20