5054_w11_qp_21
A paper of Physics, 5054
Questions:
11
Year:
2011
Paper:
2
Variant:
1
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2
shows an elevator that is supported by a cable. motor cable pulley concrete block elevator (not to scale) The cable passes around the axle of an electric motor and over a pulley. The cable is then attached to a concrete block that has the same mass as the empty elevator. As the elevator moves up, the concrete block moves down. Explain why very little work is done by the electric motor when lifting up the empty elevator. Several people of total weight 4900 N are travelling upwards at constant speed in the elevator. They rise through a distance of 24 m in 28 s. Calculate the minimum power output of the electric motor. power =
1. Motion, forces and energy  →  1.7.5. Power
1. Motion, forces and energy  →  1.7.2. Work
4. Electricity and magnetism  →  4.5.5. The d.c. motor
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3
shows the flame of a Bunsen burner. flame Bunsen burner A thermocouple thermometer contains a voltmeter. It is used to measure the temperature in the flame of the Bunsen burner. On , draw a labelled diagram of the structure of the thermocouple thermometer as it measures the temperature in the flame. Describe how the fixed points and the reading of the voltmeter are used to determine the value of the temperature in the flame. The thermocouple thermometer is used to measure the temperature in the flame because it can measure very high temperatures. State and explain one other advantage of using a thermocouple thermometer to determine temperature.
2. Thermal physics  →  2.2.1. Thermal expansion of solids, liquids and gases
2. Thermal physics  →  2.3.4. Consequences of thermal energy transfer
2. Thermal physics  →  2.2.2. Specific heat capacity
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4
shows a glass lens in air and its two focal points F1 and F2. lens three rays F1 F2 Three rays of light pass through F1 to the lens. On , continue the three rays through the lens and into the air. State what happens to the speed of light on entering the glass lens from air, leaving the lens and returning to the air. Light of wavelength 6.0 × 10–7 m travels in air at a speed of 3.0 × 108 m / s. Calculate the frequency of this light. frequency = State the effect, if any, on the frequency as the light enters the glass from air.
3. Waves  →  3.2.2. Refraction of light
3. Waves  →  3.1. General properties of waves
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5
shows a nylon rod being rubbed with a woollen cloth. rod cloth The rod becomes negatively charged. Explain how rubbing the nylon rod makes it negatively charged. State what happens to the cloth as the rod becomes negatively charged. shows the negatively-charged rod placed near to a conducting sphere. The sphere is suspended by an insulating thread. insulating thread negatively-charged rod – – – – – – – – – – – – conducting sphere On , draw the distribution of positive and negative charges on the sphere. Explain why the sphere is attracted to the rod.
4. Electricity and magnetism  →  4.2.1. Electrical charge
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6
When a car is moving, its electrical equipment is powered by an a.c. generator. The coil of the a.c. generator is rotated by the car engine. On the axes in , sketch a graph of the output voltage of the coil against time for two rotations of the coil of the generator. output voltage time 0 0 The speed of the car increases and so does the speed of rotation of the coil. State two changes that this causes to the output voltage. change 1 change 2 When the car engine is off, the current in a lamp from a 12 V battery is 0.50 A. Calculate the resistance of the lamp. resistance =
4. Electricity and magnetism  →  4.4.1. Uses of electricity
4. Electricity and magnetism  →  4.2.4. Resistance
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7
is the circuit diagram for the volume control of a loudspeaker. input voltage S C loudspeaker The circuit includes a variable potential divider . The input voltage is connected across the ends of the potential divider. The loudspeaker is connected between the sliding contact S and the terminal C. The sliding contact S is moved towards C. State and explain the effect on the sound produced. The loudspeaker emits a sound of constant pitch. Over a period of time, this sound becomes louder and louder. State the effect, if any, on the amplitude and on the frequency of the sound wave during this time. the amplitude the frequency
3. Waves  →  3.4. Sound
4. Electricity and magnetism  →  4.3.3. Action and use of circuit components
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8
One radioactive isotope of iodine is 131 53 I. As a nucleus of this isotope decays, it emits a beta-particle (symbol: β) and it becomes a nucleus of an isotope of xenon (symbol: Xe). Complete the equation in nuclide form, for this decay. 53 I Xe + β A sample of a radioactive isotope emits both beta-particles and gamma-rays. shows these two types of radiation entering a magnetic field. beta-particles and gamma-rays magnetic field into the page The direction of the magnetic field is into the page. On , mark and label the path taken by the beta-particles, the gamma-rays. Emission from a radioactive source is a random process. State two ways in which the process is random. 1. 2.
5. Nuclear physics  →  5.2.3. Radioactive decay
5. Nuclear physics  →  5.2.5. Half-life
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9
is the speed-time graph for a rocket from the moment that the fuel starts to burn at time t = 0. speed m / s 0 0 t / s State the principal energy changes taking place as the rocket accelerates upwards. State the size of the acceleration of the rocket at t = 0. State what happens to the acceleration of the rocket between t = 5 s and t = 80 s. Calculate the acceleration of the rocket at t = 80 s. acceleration = The total mass of the rocket at t = 80 s is 1.6 × 106 kg. Calculate the resultant force on the rocket at this time. resultant force = The total weight of the rocket at t = 80 s is 1.6 × 107 N. Calculate the upward force on the rocket at this time, caused by the burning fuel. upward force = As the rocket burns fuel, it ejects hot gas downwards. State Newton’s third law of motion. Explain how Newton’s third law of motion applies to the upward force on the rocket and to the force on the hot gas.
1. Motion, forces and energy  →  1.2. Motion
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10
is the circuit diagram of a fan oven that works from a 230 V a.c. mains supply. M fan motor heater 230 V a.c. supply S2 S1 The oven contains a 3500 W electric heater, an electric fan operated by a 200 W fan motor and two switches S1 and S2. When switches S1 and S2 are open, both the heater and the fan motor are off, as shown in . S1 S2 heater fan motor open open off off off on on on Complete by writing “open” or “closed” in the boxes. Explain how the circuit represented by ensures that the heater cannot be switched on when the fan motor is off. Suggest one reason why the circuit is designed so that the heater cannot be switched on when the fan motor is off. The heater and the fan motor are both switched on. Calculate the current supplied to the oven. current = 1. Suggest a suitable rating for the fuse to be used with this oven. 2. The fuse is placed in one of the three wires in the mains lead. State the wire in which it is placed. Explain how earthing the metal case of the oven makes it safer. The cost of 1 kW h of electrical energy is 35 cents. Calculate the cost of leaving just the fan motor switched on for 12 hours. cost =
4. Electricity and magnetism  →  4.4.2. Electrical safety
4. Electricity and magnetism  →  4.4.1. Uses of electricity
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11
A crankshaft is a shaped metal bar that is part of a car engine. It is free to rotate about an axis, as shown in . axis of crankshaft crankshaft direction of rotation 0.050 m P F When the crankshaft is horizontal, a vertical force F of 8200 N acts downwards on the crankshaft at P. This causes the crankshaft to rotate. The distance between P and the axis of the crankshaft is 0.050 m. State what is meant by the moment of a force. The crankshaft is horizontal. Calculate the moment of F about the axis of the crankshaft. moment = The size and direction of the vertical force F, acting on the crankshaft at P, remain constant. Explain why the moment of F decreases as the crankshaft rotates through a small angle. The force F on the crankshaft at P is exerted by a metal rod connected to a piston. The piston traps high-pressure gas in a cylinder, as shown in . high-pressure gas metal rod piston force F P cylinder The force F, of 8200 N, acts because the high-pressure gas pushes down on the piston. The air pressure outside the cylinder is 1.0 × 105 Pa and the cross-sectional area of the piston is 0.0067 m2. Calculate the minimum value of the pressure of the gas in the cylinder. pressure = Suggest why, in practice, the pressure of the gas in the cylinder is greater than the value calculated in . Question 11 continues on the next page. The piston moves in the cylinder and the gas expands. State and explain what happens to the force F. Explain, in molecular terms, why heating a gas at constant volume causes its pressure to increase.
1. Motion, forces and energy  →  1.8. Pressure
1. Motion, forces and energy  →  1.5.5. Turning effect of forces
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