RVHS_H2_Physics_P2_Soln

River Valley High School Page 1 of 8 J2 H2 Physics 9749 Preliminary Examinations 2022 RVHS JC2 H2 Physics Preliminary Examinations Paper 2 Mark Scheme 1 (a) error that does not have a fixed magnitude or direction or error that scattered around the true value. or equivalent statement B1 (b) (i) 13 cos 35𝑜 = 10.6 or 11 m s-1 B1 (ii) 𝑣𝑚𝑎𝑥 = 13 × 1.1 cos 34𝑜 = 11.9 m s-1 or 𝑣𝑚𝑖𝑛 = 13 × 0.9 cos 36𝑜 = 9.47 m s-1 B1 uncertainty = 11.9 − 10.6 ≈ ± 1 m s-1 or 10.6 − 9.47 or 11.9−9.47 2 B1 (11 ± 1) m s-1 uncertainty given to 1 sf and value given to the same precision as uncertainty B1 2 (a) No net force No net torque/moment about any point B1 B1 (b) (i) Downwards weight from centre of block Force by ball at upper left hand corner of block, follows direction of velocity of ball. Upwards normal reaction force at A (equal length to weight) Frictional force acting at A to the left B1 for bot h B1 (ii) Taking pivot about A, clockwise moments by force from ball = anticlockwise moments by weight. 9.0 × F = 300/1000 × 9.81 × 5.0 F = 1.64 N C1 M1 A1 3 (a) (i) When the gas is heated, the molecules gains kinetic energy (or speed), leading to a larger change in momentum per collision with the container per unit time. This leads to a larger force on the walls of container and piston. This leads to an increase in pressure in the container. To keep the pressure constant, the piston moves up that leads to an increase in volume of gas until the rate of change of momentum of gas molecules with the walls of the container decreases to the original level. B1 B1

River Valley High School Page 2 of 8 J2 H2 Physics 9749 Preliminary Examinations 2022 (ii) 2 3 2 0.60 28 273.15 57 273.15 0.66 m V V =++ = 1 mark for correct graph 1 mark for correct showing correct values on both axes B2 (iii) Energy from heater = (24)(15)(60) = 21600 J Using U Q W = + , Q = − 7000 + 21600 = 14600 J W = 101000(0.66 – 0.60) = 6060 J U = 14600 − 6060 = 8540 J Accept slight variation in values if using raw values from (ii) Max of 1 mark if students using alternative methods B1 C1 A1 (b) (i) Using 21 3pV Nm c= and pV NkT= , 221 32N m c NkT = 213 22E m c kT== B1 (ii) Using 213 22m c kT= , A Rk N= and AM N m= 2 3 -1 3 3 3 3(8.31)(57 273.15) 1.43 10 m s4.0 10 rms kT RTcc mM − += = = = =   C1 A1 pressure / kPa volume /m3 0.60 0.66 101

River Valley High School Page 3 of 8 J2 H2 Physics 9749 Preliminary Examinations 2022 4 (a) A progressive wave is a wave in which energy is carried from one point to another by means of vibrations or oscillations within the wave. Particles within the wave are not transported along the wave. B1 (b) (i) λ = 0.40 m since distance between P and Q is 1.5 wavelength. v = f λ = 0.40 × 850 = 34