Physics 9702/23 October/November 2024: question paper and mark scheme

Question

(a) Define acceleration. …… [1] (b) A small aircraft is flying horizontally at a speed of 42 m s–1 at a height of 63 m above horizontal ground, as shown in Fig. 1.1. speed 42 m s–1 63 m ground Fig. 1.1 The aircraft drops a small parcel. The parcel is released from the aircraft at the instant shown in Fig. 1.1. Air resistance is negligible. (i) On Fig. 1.1, draw a line to show the path of the parcel as it falls from the aircraft to the ground. [1] (ii) Calculate the time taken from the instant of release to the instant the parcel reaches the ground. time = …… s [2] (iii) Calculate the vertical component of the velocity of the parcel immediately before it reaches the ground. vertical component of velocity = …… m s–1 [1] (iv) Determine the speed at which the parcel reaches the ground. speed = …… m s–1 [2] [Total: 7]

Question

(a) State the principle of conservation of momentum. …… [2] (b) A ball X has mass 240 g and moves in a straight line on a horizontal frictionless surface with an initial speed of 16 m s–1. The ball collides with a stationary ball Y that has mass 480 g. After the collision, ball X is stationary, as shown in Fig. 2.1. ball X, ball Y, ball X, ball Y, mass 240 g mass 480 g mass 240 g mass 480 g 16 m s–1 v surface surface BEFORE AFTER Fig. 2.1 (i) Show that the speed v of ball Y after the collision is 8.0 m s–1. [1] (ii) Calculate the change in the total kinetic energy ∆EK of the balls due to the collision. ∆EK = …… J [3] (c) The collision in (b) lasts for a time of 2.0 ms. Assume that the contact force between the balls is constant during this time. (i) Determine the magnitude and direction of the force exerted on ball X by ball Y during the collision. magnitude = …… N direction …… [3] (ii) Compare the magnitude and direction of the force exerted on ball Y by ball X during the collision with the answers in (c)(i). No further calculations are required. …… [2] [Total: 11]

Question

(a) State the principle of moments. …… [1] (b) A rigid uniform beam rests on a pivot at its centre, as shown in Fig. 3.1. beam x 0.40 m wooden cylinder, weight 4.0 N pivot container h load, weight 2.6 N water Fig. 3.1 (not to scale) A load of weight 2.6 N is suspended from the beam at distance x from the pivot. A wooden cylinder of weight 4.0 N is suspended from the beam at a distance of 0.40 m from the pivot on the opposite side of the pivot to the load. The cylinder rests in a container of water. The lower part of the cylinder is immersed in the water to depth h. Initially, h is equal to 0.10 m and x is equal to 0.40 m. The system is in equilibrium. (i) Use the principle of moments to show that the upthrust U exerted by the water on the cylinder is 1.4 N. [2] (ii) The density of the water is 1.0 × 103 kg m–3. Calculate the area A of the circular cross-section of the cylinder. A = …… m2 [3] (c) More water is gradually added to the container in (b), so that depth h in Fig. 3.1 gradually increases. The length x is continuously adjusted so that the system remains in equilibrium. On Fig. 3.2, sketch the variation of x with h. Use the space below for any working. 0.8 0.6 x/m 0.4 0.2 0 0.10 0.15 0.20 0.25 0.30 0.35 0.40 h/m Fig. 3.2 [3] [Total: 9]

Question

(a) Define: (i) stress …… [1] (ii) strain. …… [1] (b) Two wires X and Y, with equal unstretched lengths of 0.84 m, are suspended from fixed points that are at the same horizontal level. The lower ends of the wires are attached to a beam of negligible mass. The beam is horizontal and in equilibrium, as shown in Fig. 4.1. wire X wire Y beam load, 18 N Fig. 4.1 Wire X is made from a metal that has a Young modulus of 1.9 × 109 Pa. Wire Y is made from a different metal. A load of weight 18 N is suspended from the beam at a point that is equidistant from the two wires. This load causes both wires to extend by 0.47 mm. (i) Determine the cross-sectional area of wire X. cross-sectional area = …… m2 [3] (ii) Wire Y has a greater diameter than wire X. Explain, without calculation, whether the Young modulus of the metal from which wire Y is made is less than, the same as or greater than 1.9 × 109 Pa. …… [2] [Total: 7]

Question

(a) A stationary wave is formed on a string XY that has a length of 0.48 m. Fig. 5.1 shows the string at one instant in time. 0.48 m X Y Fig. 5.1 The speed of the wave on the string is 1400 m s–1. (i) On Fig. 5.1, draw a cross (×) at one position that is a node and another cross at one position that is an antinode. Label the node N and the antinode A. [1] (ii) Show that the wavelength of the wave produced is 0.32 m. Explain your reasoning. [1] (iii) Calculate the frequency of the wave. frequency = …… Hz [2] (b) A source of sound waves of frequency 780 Hz is on a rotating platform. The speed of the source is 39 m s–1. The sound is detected by an observer that is a large distance from the rotating platform, as shown in Fig. 5.2. source of sound, observer speed 39 m s–1 platform Fig. 5.2 (not to scale) (i) The speed of sound in air is 320 m s–1. Calculate the maximum frequency of the sound detected by the observer. maximum frequency = …… Hz [2] (ii) At time t = 0, the observer detects the sound emitted by the source when it was in the position shown in Fig. 5.2. On Fig. 5.3, sketch the variation with t of the frequency f of the sound detected by the observer for one complete rotation of the platform. Calculations are not required. f 0 t Fig. 5.3 [2] [Total: 8]

Question

(a) Define resistance. …… [1] (b) A cylindrical metal wire of length 2.4 m and cross-sectional area 8.0 × 10–6 m2 has a resistance of 0.33 Ω. There is a current in the wire of 4.7 A. (i) Determine the resistivity of the metal from which the wire is made. resistivity = …… Ω m [2] (ii) Calculate the charge that passes through the wire in a time of 5.0 minutes. charge = …… C [2] (iii) The free electrons (charge carriers) in the wire have an average drift speed of 0.16 mm s–1. Determine the number density of charge carriers in the metal. number density = …… m–3 [2] (c) The wire in (b) may be considered to be a fixed resistor. It is connected in series with a thermistor to a battery that has negligible internal resistance. (i) Use circuit symbols to complete Fig. 6.1 to show the circuit diagram of this arrangement. Fig. 6.1 [1] (ii) Explain, without calculation, how the power dissipated in the wire changes as the temperature of the thermistor is increased. …… [2] [Total: 10]

Question

(a) Complete Table 7.1 to show the charges, in terms of the elementary charge e, on each of the flavours of quark and antiquark shown. Table 7.1 charge / e flavour quark antiquark up down strange [3] (b) (i) State the name of the class (group) of fundamental particles to which baryons and mesons belong. …… [1] (ii) Compare baryons and mesons in terms of their constituent particles. …… [2] (c) Describe β+ decay in terms of the fundamental particles involved. …… [2] [Total: 8]