Physics 9702/22 February/March 2019: question paper and mark scheme

Question

(a) The ampere, metre and second are SI base units. State two other SI base units. 1. …… 2. …… [2] (b) The average drift speed v of electrons moving through a metal conductor is given by the equation: μF v= e where e is the charge on an electron F is a force acting on the electron and μ is a constant. Determine the SI base units of μ. SI base units ……[3] [Total: 5]

Question

(a) Define: (i) displacement ……[1] (ii) acceleration. ……[1] (b) A man wearing a wingsuit glides through the air with a constant velocity of 47 m s–1 at an angle of 24° to the horizontal. The path of the man is shown in Fig. 2.1. 47 m s–1 A man in wingsuit glide path total mass 85 kg h 24° B horizontal Fig. 2.1 (not to scale) The total mass of the man and the wingsuit is 85 kg. The man takes a time of 2.8 minutes to glide from point A to point B. (i) With reference to the motion of the man, state and explain whether he is in equilibrium. ……[2] (ii) Show that the difference in height h between points A and B is 3200 m. [1] (iii) For the movement of the man from A to B, determine: 1. the decrease in gravitational potential energy decrease in gravitational potential energy = …… J [2] 2. the magnitude of the force on the man due to air resistance. force = …… N [2] (iv) The pressure of the still air at A is 63 kPa and at B is 92 kPa. Assume the density of the air is constant between A and B. Determine the density of the air between A and B. density = …… kg m–3 [2] [Total: 11]

Question

Two balls, X and Y, move along a horizontal frictionless surface, as illustrated in Fig. 3.1. 60° 3.0 m s–1 X A B 9.6 m s–1 Y 2.5 kg Fig. 3.1 (not to scale) Ball X has an initial velocity of 3.0 m s–1 in a direction along line AB. Ball Y has a mass of 2.5 kg and an initial velocity of 9.6 m s–1 in a direction at an angle of 60° to line AB. The two balls collide at point B. The balls stick together and then travel along the horizontal surface in a direction at right-angles to the line AB, as shown in Fig. 3.2. V X Y A B Fig. 3.2 (a) By considering the components of momentum in the direction from A to B, show that ball X has a mass of 4.0 kg. [2] (b) Calculate the common speed V of the two balls after the collision. V = …… m s–1 [2] (c) Determine the difference between the initial kinetic energy of ball X and the initial kinetic energy of ball Y. difference in kinetic energy = …… J [2] [Total: 6]

Question

(a) Define electric field strength. ……[1] (b) Two very small metal spheres X and Y are connected by an insulating rod of length 72 mm. A side view of this arrangement is shown in Fig. 4.1. +3e uniform electric field, X field strength 5.0 × 104 V m–1 72 mm in vertically upwards direction θ horizontal Z θ SIDE rod VIEW Y –3e Fig. 4.1 (not to scale) Sphere X has a charge of +3e and sphere Y has a charge of –3e, where e is the elementary charge. The rod is held at its mid point Z at an angle θ to the horizontal. The rod and spheres have negligible mass and are in a uniform electric field. The electric field strength is 5.0 × 104 V m–1. The direction of this field is vertically upwards. (i) The electric field is produced by applying a potential difference of 4.0 kV between two charged parallel metal plates. 1. Calculate the separation between the plates. separation = …… m [2] 2. Describe the arrangement of the two plates. Include in your answer a statement of the sign of the charge on each plate. You may draw on Fig. 4.1. ……[2] (ii) Determine the magnitude and direction of the force on sphere Y. magnitude = …… N direction …… [2] (iii) The electric forces acting on the two spheres form a couple. This couple acts on the rod with a torque of 6.2 × 10–16 N m. Calculate the angle θ of the rod to the horizontal. θ = …… ° [2] [Total: 9]

Question

(a) By reference to two waves, state: (i) the principle of superposition ……[2] (ii) what is meant by coherence. ……[1] (b) Two coherent waves P and Q meet at a point in phase and superpose. Wave P has an amplitude of 1.5 cm and intensity I. The resultant intensity at the point where the waves meet is 3I. Calculate the amplitude of wave Q. amplitude = …… cm [2] (c) The apparatus shown in Fig. 5.1 is used to produce an interference pattern on a screen. laser light wavelength 680 nm a D double-slit screen Fig. 5.1 (not to scale) Light of wavelength 680 nm is incident on a double-slit. The slit separation is a. The separation between adjacent fringes is x. Fringes are viewed on a screen at distance D from the double-slit. Distance D is varied from 2.0 m to 3.5 m. The variation with D of x is shown in Fig. 5.2. 10.0 8.0 x / mm 6.0 4.0 2.0 0 2.0 2.5 3.0 3.5 D/m Fig. 5.2 (i) Use Fig. 5.2 to determine the slit separation a. a = …… m [3] (ii) The laser is now replaced by another laser that emits light of a shorter wavelength. On Fig. 5.2, sketch a possible line to show the variation with D of x for the fringes that are now produced. [2] [Total: 10]

Question

(a) Using energy transformations, describe the electromotive force (e.m.f.) of a battery and the potential difference (p.d.) across a resistor. e.m.f.: …… p.d.: …… ……[2] (b) A battery of e.m.f. 6.0 V and negligible internal resistance is connected to a network of resistors and a voltmeter, as shown in Fig. 6.1. Z V 32 Ω 6.0 V X Y 24 Ω Fig. 6.1 Resistor Y has a resistance of 24 Ω and resistor Z has a resistance of 32 Ω. (i) The resistance RX of the variable resistor X is adjusted until the voltmeter reads 4.8 V. Calculate: 1. the current in resistor Z current = …… A [1] 2. the total power provided by the battery power = …… W [2] 3. the number of conduction electrons that move through the battery in a time interval of 25 s number = …… [2] 4. the total resistance of X and Y connected in parallel total resistance = …… Ω [2] 5. the resistance RX. RX = …… Ω [2] (ii) The resistance RX is now decreased. State and explain the change, if any, to the reading on the voltmeter. ……[2] [Total: 13]

Question

(a) The names of four particles are listed below. alpha beta-plus neutron proton State the name(s) of the particle(s) in this list that: (i) are not fundamental ……[1] (ii) do not experience an electric force when situated in an electric field ……[1] (iii) has the largest ratio of charge to mass. ……[1] (b) A hadron has a charge of +e where e is the elementary charge. The hadron is composed of only two quarks. One of these quarks is an antidown ( d ) quark. By considering charge, state and explain the name (flavour) of the other quark. ……[3] [Total: 6]