2024 SCGS 4 IP PHYSICS P1+P2 ANS

2024 4 IP EOY SUGGESTED ANSWER SCHEME PAPER 1 (40 marks) Qn Answer Explanation 1 C Acceleration and Weight are vectors while the rest are scalars. 2 D T: Density = 10/ 8.0 = 1.25 g/cm3 U: Density = 10/ 12.0 = 0.83 g/cm3 V: Density = 20/ 16.0 = 1.25 g/cm3 W: Density = 20/ 8.0 = 2.5 g/cm3 3 B By completing the parallelogram, resultant will be the diagonal. 4 A As the ball drops vertically it undergoes constant acceleration due to free fall, hence the first part of the graph must be a straight line of constant gradient. When the ball hits the ground and rebounds in the opposite direction, its velocity drops to zero and as it rebounds in the opposite direction, the graph shows a drop to zero velocity and then a negative velocity. Subsequently, it goes upwards with a constant gradient. 5 B v / t = a v / 2.0 s = 10 m/s2 v = 20 m/s area under velocity – time graph gives you displacement hence h = ½ x 20 x 2.0 = 20 m 6 D a = (v – u )/t 2.0 m/s2 = (v - 5.0 m/s )/ 10s v = 25 m/s 7 B Fnet = ma 2N – 1N = 10a a = 0.1 m/s2 8 C Action and reaction pair act at the same time, on mutually different bodies, have the same magnitude but opposite directions. 9 C Since there is no air resistance, both divers will fall with the same acceleration due to gravity and hence will have the same velocity before they the water. Distance travelled is obviously the same as they both jump from the same height. As energy in kinetic store = ½ x m x v2; since their mass are different, their energy in kinetic store will be different. 10 A Rate of work done against air resistance = Force x Distance / time = 3.0 N x (1/2 x 5.0 m/s x 10s) /10s = 7.5 W

11 B P = mgh/t . Larger mass of ball lifted to a greater height will require greater power when time taken to pick the ball is the same for all four. 12 D Steam from the boiler turns the turbines. 13 C Applying principle of moments, 6.0 N x 10 cm + 4.0 N x 30 cm = 5.0 N x d  d = 36 cm The 5.0 N weight is acting at the 86 cm mark 14 B Bar 2 , Take moments about any one of two edges will result in either a clockwise or anticlockwise moment. 15 A Height change of P and Q = 20 m ; Height change of R and S = 40 m 16 D Since the mercury level in both arms are at the same level, pressure exerted by liquid X column = Pressure exerted by liquid Y column. From hXX = hYY, hX > hY Y > pX 17 B Height of the barometer is independent of the cross-sectional area. 18 A Molecules cannot expand (statement 1 incrorrect). They cannot move further apart as the volume if fixed ( statement 4 incorrect). 19 C A is radiation; B is conduction ; C is radiation and conduction 20 D Pressure of gas X > Patm to cause the piston to move. After opening its pressure will reduce to the same as Patm but not lesser for that will shift the piston inwards. Nor will the pressure be more