OPSS 4NA Prelim Physics Ans

Orchid Park Secondary School Sec 4NA Preliminary Examination 2022 Science (Physics) Answer Scheme Paper 1 No Answer No Answer 1 D 11 A 2 A 12 C 3 B 13 C 4 A 14 C 5 C 15 B 6 C 16 D 7 D 17 B 8 A 18 B 9 C 19 A 10 B 20 B Paper 2 Ques Answer Marks 1a Force X – friction/air resistance Force Y- weight B1 1b Equal in size B1 2a Electronic balance/beam balance B1 2b Block X. Area of contact between block X and the table is smaller, hence greater pressure exerted. B1 2c Volume = 2 x 2 x 2 = 8 cm3 Density = m/V= 5/8 = 0.625 cm3 A1 3a Transverse: Light, Radiowave Longitudinal: Sound B1 3b Wavelength = 3.3 cm Amplitude = 1.0 cm B2 3c The vibrations from the prong causes the air particles around it the vibrate, resulting in regions of compressions and rarefaction. The sound is longitudinal in nature as the sound waves travel to the ear of the listener parallel to direction of vibration of the air particles. B1 B1 4ai Black as black surfaces are good absorber of radiation B1 4aii Increase surface area to increase rate of absorption. B1 4b The air near the radiator gain heat, expand, becomes less dense and rises . The cooler, denser air at the top sinks to replace the rising hot air. B1

2 [Turn over setting up a convection current to help warm up the rest of the room. B1 5a Scalar. It has magnitude but not direction. B1 5b acceleration = 𝑣−𝑢 𝑡 = 6−0 4 =1.5 m/s2 C1 A1 5ci Increasing speed/ accelerating B1 5cii Constant speed B1 5d Distance = area under graph = ½ x 6 x 4 = 12 m C1 A1 5e Gravitational potential energy converts to kinetic and thermal energy. B1 6a wheel B1 6bi Less than 500 N. Effort is further away from the pivot than the load of 500 N B1 6bii Place the 500 N load nearer to the pivot. Exert the effort further from the pivot. B1 B1 6c Work done = force x distance = 500 x 1.5 = 750 J C1 A1 6d W = mg 500 = m x 10 m = 50 kg A1 6e KE = ½ mv2 = ½ x 50 x 32 = 225 J A1 7ai Plotted points Best fit line M1 A1 7aii R = V/I = 9.6/0.6 =16 Ω C1 A1 7b Long piece of wire – high resistance Short piece of wire- low resistance Thin wire – high resistance Thick wire – low resistance B1 B1 7c Neutral wire is connected to the Earth pin Earth wire is connected to the neutral pin Fuse is missing B2