DHS 2023 Prelim Physics (Paper 1 Solutions)

DUNMAN HIGH SCHOOL 2023 H2 PHYSICS (YEAR 6) 1 Answers to Prelim Exam H2 Physics Paper 1 1 2 3 4 5 6 7 8 9 10 A B B D A B C C D C 11 12 13 14 15 16 17 18 19 20 A C D B D D B A B B 21 22 23 24 25 26 27 28 29 30 D C A D C C A A B D 1 A energy = power x time = 3.0 x 109 x 2.0 x 10-12 = 6.0 x 10-3 J = 6.0 x 10-15 TJ 2 B Recall: v = vf - vi The horizontal component of vi = vf since there’s no horizontal acceleration, so v is vertical. v = 12 sin 25o = 5.1 m s-1 3 B Before time instant B, the cars are moving towards each other. After time instant B, they are moving away from each other. 4 D Kinetic energy is conserved only if the collision is elastic. Hence, only momentum and total energy is conserved as there are no net external forces acting on the system when the two objects collide. 25o vf -vi = 12 m s-1 v

DUNMAN HIGH SCHOOL 2023 H2 PHYSICS (YEAR 6) 2 5 A By considering the free body diagrams of the 5.0 kg and 3.0 kg masses: 55 33 g T a T g a −= −= .( 1 28 1 4 2 5 m s to 2 s.f.) ga ag − = = = 6 B Taking moments about the pivot, W (0.900 ) (1.60 ) [ (4.00 )( ) ](0.900 ) [ ( )( ) ](1.60 ) (4.00)(0.900) (1.60) 4.00(0.900) 1.60 2.25 wood rubber wood rubber wood rubber rubber wood L W L L A g L L A g L    = = = = = 3.0 kg 5.0 kg 3g 5g T T 2.90 L 2.10 L Wood Rubber WRubber WWood 2.00 L 0.50 L

DUNMAN HIGH SCHOOL 2023 H2 PHYSICS (YEAR 6) 3 7 C (0.50)(1000)(9.81 ) 4910 Pap hpg = = = 8 C The work done by the driving force F was used to increase the car ’s kinetic energy as it gains speed from u to v. Hence the useful work done by the force F is equals to the increase in KE of the car. 9 D 2D kv= ,where k is a constant of proportionality At 12 m s-1, the driving force provided by the 2 engines is equal and opposite to the total drag. () () 3 3 36000 2 12 720000 12 P Dv k k = = = If only 1 engine is on, the new maximum speed v’ can be found by: 3 3 33 1 3 720000360000 ( ') (12) 360000' (12 )720000 12 9.5 m s 2 v v − = = == 10 C At Q, 2mvN mg r+= As the bead is just in contact with the wire, N = 0. Thus, 2 0.20v rg g== Using conservation of energy, 21 (0.40)2 1 (0.20 ) (0.40)2 0.50 m mgh mv mg mgh m g mg h =+ =+ =

DUNMAN HIGH SCHOOL 2023 H2 PHYSICS (YEAR 6) 4 11 A period of rotation = 365 days 7 -1 11 7 4 -1 22 1.99 10 rad s(365 24 60 60) (1.50 10 )(1.99 10 ) 2.99 10 m s T vr   − − = = =   = =   =  12 C Gravi