9702_s06_qp_2
A paper of Physics, 9702
Questions:
8
Year:
2006
Paper:
2
Variant:
0
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1
Derive the SI base unit of force. SI base unit of force = ………………………………… A spherical ball of radius r experiences a resistive force F due to the air as it moves through the air at speed v. The resistive force F is given by the expression F = crv, where c is a constant. Derive the SI base unit of the constant c. SI base unit of c = ………………………………… [T The ball is dropped from rest through a height of 4.5 m. Assuming air resistance to be negligible, calculate the final speed of the ball. speed = …………………………… m s–1 The ball has mass 15 g and radius 1.2 cm. The numerical value of the constant c in the equation in is equal to 3.2 ×10–4 when measured using the SI system of units. Show quantitatively whether the assumption made in is justified. Examiner s Use
1. Physical quantities and units  →  1.2. SI units
15. Ideal gases  →  15.1. The mole
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2
A rod AB is hinged to a wall at A. The rod is held horizontally by means of a cord BD, attached to the rod at end B and to the wall at D, as shown in . The rod has weight W and the centre of gravity of the rod is at C. The rod is held in equilibrium by a force T in the cord and a force F produced at the hinge. Explain what is meant by the centre of gravity of a body, the equilibrium of a body. Use B A D cord rod wall hinge C P T F W [T The line of action of the weight W of the rod passes through the cord at point P. Explain why, for the rod to be in equilibrium, the force F produced at the hinge must also pass through point P. The forces F and T make angles α and β respectively with the rod and AC =  AB, as shown in . Write down equations, in terms of F, W, T, α and β, to represent the resolution of forces horizontally, the resolution of forces vertically, the taking of moments about A. Examiner s Use
4. Forces, density and pressure  →  4.2. Equilibrium of forces
4. Forces, density and pressure  →  4.1. Turning effects of forces
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4
[T Define density. A U-tube contains some mercury. Water is poured into one arm of the U-tube and oil is poured into the other arm, as shown in . The amounts of oil and water are adjusted until the surface of the mercury in the two arms is at the same horizontal level. State how it is known that the pressure at the base of the column of water is the same as the pressure at the base of the column of oil. The column of water, density 1.0 × 103kg m–3, is 53 cm high. The column of oil is 71 cm high. Calculate the density of the oil. Explain your working. density = ………………………………. kg m–3 Use 71 cm 53 cm water oil mercury
4. Forces, density and pressure  →  4.3. Density and pressure
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5
shows the variation with force F of the extension x of a spring as the force is increased to F3 and then decreased to zero. State, with a reason, whether the spring is undergoing an elastic change. The extension of the spring is increased from x1 to x2. Show that the work W done in extending the spring is given by W =  k(x2 2 – x1 2), where k is the spring constant. Use F1 x1 x2 x F2 F3 F [T A trolley of mass 850 g is held between two fixed points by means of identical springs, as shown in . When the trolley is in equilibrium, the springs are each extended by 4.5 cm. Each spring has a spring constant 16 N cm–1. The trolley is moved a distance of 1.5 cm along the direction of the springs. This causes the extension of one spring to be increased and the extension of the other spring to be decreased. The trolley is then released. The trolley accelerates and reaches its maximum speed at the equilibrium position. Assuming that the springs obey Hooke’s law, use the expression in to determine the maximum speed of the trolley. speed = …………………………. m s–1 Examiner s Use trolley spring
6. Deformation of solids  →  6.1. Stress and strain
6. Deformation of solids  →  6.2. Elastic and plastic behaviour
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6
A long tube, fitted with a tap, is filled with water. A tuning fork is sounded above the top of the tube as the water is allowed to run out of the tube, as shown in . A loud sound is first heard when the water level is as shown in , and then again when the water level is as shown in . illustrates the stationary wave produced in the tube. On , sketch the form of the stationary wave set up in the tube, mark, with the letter N, the positions of any nodes of the stationary wave. Use 32.4 cm tuning fork 512 Hz [T The frequency of the fork is 512 Hz and the difference in the height of the water level for the two positions where a loud sound is heard is 32.4 cm. Calculate the speed of sound in the tube. speed = …………………… m s–1 The length of the column of air in the tube in is 15.7 cm. Suggest where the antinode of the stationary wave produced in the tube in is likely to be found. Examiner s Use
8. Superposition  →  8.1. Stationary waves
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7
A circuit contains three similar lamps A, B and C. The circuit also contains three switches, S1, S2 and S3, as shown in . One of the lamps is faulty. In order to detect the fault, an ohm-meter (a meter that measures resistance) is connected between terminals X and Y. When measuring resistance, the ohm- meter causes negligible current in the circuit. shows the readings of the ohm-meter for different switch positions. Identify the faulty lamp, and the nature of the fault. faulty lamp: nature of fault: Suggest why it is advisable to test the circuit using an ohm-meter that causes negligible current rather than with a power supply. Use A C B S2 S1 S3 X Y open closed open open ∞ 15 Ω 30 Ω 15 Ω open open closed closed open open open closed switch S1 S2 S3 meter reading / Ω [T Determine the resistance of one of the non-faulty lamps, as measured using the ohm- meter. resistance = …………………… Ω Each lamp is marked 6.0 V, 0.20 A. Calculate, for one of the lamps operating at normal brightness, its resistance, resistance = …………………… Ω its power dissipation. power = …………………… W Comment on your answers to and . Examiner s Use
9. Electricity  →  9.3. Resistance and resistivity
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