0625_s08_qp_2 - revisedeck

0625_s08_qp_2

A paper of Physics, 0625

Questions:

12

Year:

2008

Paper:

2

Variant:

0

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1

For Examiner’s Use shows a uniform rod. Use your rule to find the length of the rod. length = cm On , show the position of the centre of mass of the rod using the letter C. shows another rod, of the same length as the previous one, but this rod is thicker at one end. Use your judgement to mark with the letter M approximately where the centre of mass of this rod will be.

1. Motion, forces and energy → 1.5.3. Centre of gravity

1. Motion, forces and energy → 1.1. Physical quantities and measurement techniques

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2

For Examiner’s Use A motorcyclist is travelling along a country road, as shown in . 1375 m A B The statements below describe the motion of the motorcycle from point A to point B. 1. The motorcycle accelerates uniformly from rest at point A, increasing its speed to 25 m/s in 10 s. 2. It then travels at a constant speed of 25 m/s for 40 s. 3. It then decelerates uniformly to rest at point B, 70 s after leaving point A. time/s speed m/s For the motorcycle moving from point A to point B, draw on , a suitable time scale, the graph of the motion of the motorcycle. The distance from A to B is 1375 m. Calculate the average speed of the motorcycle between A and B. Give your answer to the nearest m/s. average speed = m/s

1. Motion, forces and energy → 1.2. Motion

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3

For Examiner’s Use A beam is pivoted at its centre. Three forces, F1, F2 and F3, act on the beam as shown in . a c b F1 F2 F3 Which of the forces exerta clockwise moment, an anticlockwise moment? When the beam is released, the right-hand side of the beam starts to go down. Which of the three distances, a, b or c, should be decreased in order to balance the beam? Explain your answer. Which distance? Explanation represents a simple beam-balance with the pivot accurately at its centre. ? The person using the beam-balance puts the object to be weighed in the left-hand pan. He has a selection of standard masses to put in the right-hand pan, but he finds he cannot exactly balance the beam. His best attempts are masses used effect 10 g, 10 g, 5 g, 2 g, 2 g beam tips down slightly on the left-hand side 20 g, 10 g beam tips down slightly on the right-hand side Estimate the mass of the object. mass = g

1. Motion, forces and energy → 1.5.2. Turning effect of forces

1. Motion, forces and energy → 1.3. Mass and weight

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4

For Examiner’s Use An electrician climbs up to the platform of a special tower, in order to reach a high-level spotlight, as shown in . Which form of energy, possessed by the electrician’s body, is greater at the top of the tower than it was at the bottom, is less at the top of the tower than it was at the bottom? One of the electrician’s assistants also climbs up to the platform. The assistant weighs less than the electrician. Which of the two people does the most work climbing up to the platform, and why? Which person? Why? The electrician wishes to know what power he develops as he climbs the tower. Which quantities does he need to know in order to do this?

4. Electricity and magnetism → 4.2.5. Electrical energy and electrical power

2. Thermal physics → 2.3.3. Radiation

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5

For Examiner’s Use In the atomic model, the atom has a central mass. Much smaller particles orbit this central mass, as shown in . central mass orbiting particles State the name given to the central mass. State the name given to the orbiting particles. State the names of the particles from which the central mass is made. and The central mass of the helium atom is identical to one of the particles emitted in radioactive decay. Which particle is this? State the name of the particles that form cathode rays.

5. Nuclear physics → 5.1.2. The nucleus

5. Nuclear physics → 5.1.1. The atom

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6

For Examiner’s Use and show two of the rays from the top of an object, passing through a lens. F2 object F1 F2 object F1 On , draw the third ray whose path from the top of the object through the lens is known. On , copy the ray shown on and complete the diagram to locate the image formed by the lens, mark and label the image. On , indicate clearly where you would position a screen on which to see the focused image.

3. Waves → 3.2.3. Thin lenses

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7

For Examiner’s Use The table below describes the conditions of the molecules of a substance in each of the three states of matter, solid, liquid and gas. In the right-hand column, write the state of the substance that is described in the left- hand column. condition of the molecules state in which the substance exists The molecules are a great distance apart, moving very rapidly, with negligible interaction. The substance occupies all the space available. The molecules are only able to vibrate rapidly about fixed positions. The substance does not need a container to maintain its shape. The molecules move about amongst each other, with attractive forces between them. The substance does not necessarily fill its container. What is the state of matter just before a substance boils? Describe what happens to the molecules during boiling. State two differences between boiling and evaporating. 1. 2. What is the state of matter just before a substance melts? Aluminium melts at 660 °C. At what temperature does it freeze?

2. Thermal physics → 2.2.3. Melting, boiling and evaporation

2. Thermal physics → 2.1.1. States of matter

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8

For Examiner’s Use The thermometer in is calibrated at two fixed points, and the space between these is divided into equal divisions. -10 A thermometer is being calibrated with the Celsius scale. 1. Write down another name for the lower fixed point. 2. How is this temperature achieved? 3. What is the temperature of this fixed point? 1. Write down another name for the upper fixed point. 2. How is this temperature achieved? 3. What is the temperature of this fixed point? A block of copper and a block of aluminium have identical masses. They both start at room temperature and are given equal quantities of heat. When the heating is stopped, the aluminium has a lower temperature than the copper. Fill in the missing words in the sentence below, to explain this temperature difference. The aluminium block has a smaller temperature rise than the copper block because the aluminium block has a larger than the copper block.

2. Thermal physics → 2.1.3. Gases and the absolute scale of temperature

2. Thermal physics → 2.2.3. Melting, boiling and evaporation

2. Thermal physics → 2.2.2. Specific heat capacity

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9

For Examiner’s Use Fuses are often included in circuits. In the space below, draw the circuit symbol for a fuse. When the statements in the boxes below are put in the correct order, they describe how a fuse protects a circuit. A fuse wire heats up B circuit is broken, so current stops C fuse wire melts D current becomes too high On the line below, list the letters of the four boxes in the correct order. By mistake, a fuse with too high a rated value is put in the fuse-holder in a circuit. State two possible outcomes of this mistake. 1. 2.

4. Electricity and magnetism → 4.4. Electrical safety

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10

For Examiner’s Use 10 shows a series circuit. R1 X Y R2 Resistance R1 = 25 Ω and resistance R2 = 35 Ω. The cell has zero resistance. Calculate the combined resistance of R1 and R2. resistance = Ω On , use the correct circuit symbol to draw a voltmeter connected to measure the potential difference between X and Y. The variable resistor is set to zero resistance. The voltmeter reads 1.5 V. Calculate the current in the circuit. current = State the value of the potential difference across the cell. potential difference = V For Examiner’s Use The resistance of the variable resistor is increased. What happens to the current in the circuit? Tick one box. increases stays the same decreases What happens to the voltmeter reading? Tick one box. increases stays the same decreases State the resistance of the variable resistor when the voltmeter reads 0.75 V. resistance = Ω

4. Electricity and magnetism → 4.2.4. Resistance

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11

For Examiner’s Use 11 An experimenter uses a length of wire ABC in an attempt to demonstrate electromagnetic induction. The wire is connected to a sensitive millivoltmeter G. A B C G N S Using the arrangement in , the experimenter finds that she does not obtain the expected deflection on G when she moves the wire ABC down through the magnetic field. Explain why there is no deflection shown on G. What change should be made in order to observe a deflection on G? Name one device that makes use of electromagnetic induction.

4. Electricity and magnetism → 4.5.1. Electromagnetic induction

4. Electricity and magnetism → 4.5.4. Force on a current-carrying conductor

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12

For Examiner’s Use 12 The table below shows how the activity of a sample of a radioactive substance changes with time. time/minutes activity counts/s Use the data in the table to estimate the half-life of the radioactive substance. half-life = min The half-lives of various substances are given below. radon-220 55 seconds iodine-128 25 minutes radon-222 3.8 days strontium-90 28 years If the radioactive substance in is one of these four, which one is it? A sample of each of these substances is obtained. Which sample will have the greatest proportion of decayed nuclei by the end of one year, and why? Which? Why?

5. Nuclear physics → 5.2.4. Half-life

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