DHS 2022 JC1 Promos Physics (Paper 1 Solutions)

DUNMAN HIGH SCHOOL 2022 H2 PHYSICS (YEAR 5) 2022 DHS H2 Physics Promo Exam Mark scheme Section A Multiple Choice Questions 1 2 3 4 5 6 7 8 9 10 D A D C B C A C C D 11 12 13 14 15 D B B A B 1 Answer: D A is precise and accurate, B is not precise and accurate, C is not precise and not accurate. 2 Answer: A From first principles, 1 average 11( ) 40 mm50 200f −= + = 1 max 11( ) 37.9 mm47 195f −= + = max average 40.0 37.9 2.1 mmf f f = − = − = 3 Answer: D 2 2 1Using ' ', 2 110.0 0 (9.81)2 1.43 s s ut at t t =+ =+ = 22 2 -1 Using ' 2 ', 0 2(9.81)(10.0) 14.0 m s v u as v v =+ =+ =

DUNMAN HIGH SCHOOL 2022 H2 PHYSICS (YEAR 5) 4 Answer: C XY XY Y X on Y Y XY acceleration of (X+Y), , ( ) is also the acceleration of X (or Y) (so A is incorrect) isolate Y: Fa m mmm a mF m a F mm F = + ==  +  Y on X (so B is incorrect) < (so C is correct) (so D is incorrect) F F=− 5 Answer: B assume X moves to the left with speed ' after collision; elastic head-on collision relative speed of approach relative speed of seperation 0 0.67 ' ' 0.67 0.33 X moves to the left with speed v v v v v v v v =  − = +  = − =  0.33 v 6 Answer: C The work done on the sample is the area under the graph. At x = 10.0 cm, 11(60)(0.06) (60 70)(0.10 0.06)22 4.4 J W = + + − = 7 Answer: A U = mg U = (80.0 x 9.81) V air g = 80.0 x 9.81, so V= 65 m3 Balloon & mass Weight, mg Upthrust, U

DUNMAN HIGH SCHOOL 2022 H2 PHYSICS (YEAR 5) 8 Answer: C D is incorrect as the velocity changes throughout the motion, hence momentum changes. C is correct as the kinetic energy is converted to gravitational potential energy on the upward journey and vice versa on the downward journey. B is incorrect as the kinetic energy at the highest point is 0. A is incorrect as the potential energy increases uniformly with height but not time. 9 Answer: C ( )( ) ( )( ) 1 2 3 22 1 22 21 let the tensions in the rightmost, centre, and leftmost rod be , and respectiv ely, for the rightmost mass: 1.0 kg 4.0 m 4.0 for the centre mass: 1.0 kg 3.0 m 3.0 for the leftmost m T T T T TT   == − = = ( )( ) ( ) ( ) ( ) 22 32 2 2 2 3 2 1 2 2 2 22 ass: 1.0 kg 2.0 m 2.0 combining the above, we have 2.0 3.0 2.0 4.0 3.0 2.0 9.0 9.0 2.0 36 TT T T T         − = = = + = + + = + + == = N, which