PLMGSS_2022_4NA_ScPhy Prelim P1 _ P2 Mark Scheme

Prelim 4NA 2022 Solution Paper 1 1 2 3 4 5 B D A D C 6 7 8 9 10 C A D B B 11 12 13 14 15 C D C A A 16 17 18 19 20 C C A B D Paper 2 (Section A) Qns Marks 1a Cyclist B B1 1b Acceleration = (0 – 5)/4 = - 1.25 m/s2 Max 1m if positive acceleration is given M1 A1 2a B1 2b Block B and C Their line of action of the weight lies within its base area. Therefore, no moment is produced/ no turning effect. M1 A1 3a Emf is the amount of work done per unit charge needed to move a charge around the circuit. B1 3b Current in Q = 0.15 A Current in resistor = 0.15 A x 2 = 0.3 A M1 A1 4a Work done = mgh = 500 x 3 = 1500 J M1 A1

4b Mgh = 800 x 3 = 2400 J Kinetic energy = 0.5 x 80 x v2 = 2400 V2 = 60 V = 7.75 m/s M1 A1 4c He needs to have some speed when he leaves point A/ he needs to push himself before leaving ramp. A1 Paper 2 (Section B) Qns Marks 5a Longitudinal waves are waves that travel in the direction parallel to its vibration. B1 5bi Give marks only if frequency is constant and amplitude has decreased. B1 5bii Frequency increased/doubled/ pitch increased/doubled B1 5ci/5cii M1 A1 5ciii 82 – 86 dB B1 5civ 8 – 16 hours (depends on 5ciii) ecf B1

5cv Stand further away/ wear ear plugs B1 6ai Variable resistor/ rheostat B1 6aii Varies resistance/ changes the current in the circuit B1 6b Resistance = V/I = 1 / 0.5 = 2 Ω B1 6ci Upper Limit = 2 V B1 6cii It cannot exceed the emf of the battery B1 6d p.d. reading/ V Current reading/ A 1.80 0.10 1.4 0.30 1.00 0.5 B1 each B2 6e Live wire. B1 7a B1 7b Both the magnitude of each force is the same. B1 7c Chemical Potential Energy, Gravitational Potential Energy B1 B1 7di KE = 0.5 x 0.5 x 302 = 225 J M1 A1 7dii Area under graph = 0.5 x 30 x 6 = 90 m M1 A1 Weight Thrust/Lift