ACSI 2019 Y3 IP Physics Paper2

1 END-OF-YEAR EXAMINATION 2019 YEAR 3 INTEGRATED PROGRAMME PHYSICS PAPER 2 Monday 7 October 2019 1 hour 45 minutes INSTRUCTIONS TO STUDENTS Write your index number in the box provided on the top right corner of this page. Do not open this booklet until you are told to do so. Section A Answer all questions in the spaces provided in the paper. Section B Answer all questions in the spaces provided in the paper. INFORMATION FOR STUDENTS Candidates are reminded that all quantitative answers should include appropriate units. Candidates are advised to show their answers in a clear and orderly manner as more marks are awarded for sound use of physics than for correct answers. The number of marks is given in brackets [ ] at the end of each question or part question. Take g = 10 N kg-1. Calculators are allowed for this paper. There are 24 printed pages. Marks Awarded Section Marks A B Penalty Sig. Fig. Units TOTAL SCORE Index Number

2 Section A [50 Marks] A1 A 6.0 kg parcel is dropped off vertically from a helicopter 800 m above the ground. Its parachute is activated some time after the fall. The speed -time graph for the first 25 seconds of its journey is shown in Fig. A1.1. Fig. A1.1 (a) Explain what is meant by “The Earth’s gravitational field strength has a magnitude of 10 N kg-1”. [1] speed / m s-1 time / s

3 (b) Explain, in terms of forces, why the parcel’s velocity increased immediately after being dropped. [2] (c) State the time at which the parcel first achieves terminal velocity. [1] (d) Draw a labelled diagram to show all the forces that act on the parcel at t = 15 s. Indicate the values of these forces on your diagram. [2] (e) As the parcel falls, the Earth exerts a downward force on the parcel. Name the reaction force in the action-reaction pair of forces. [1]

4 A2 A ball of weight W in equilibrium is suspended by two ropes at points A and B as shown in Fig. A2.1 (not drawn to scale). The tension in the ropes are 870 N and 500 N. Fig. A2.1 (a) What is the resultant force acting on the weight W? [1] (b) By means of a scaled diagram, determine the weight W. [4] State the scale used. Scale : 870 N 500 N 60  30  A B

5 (c) State the effect on the tension of each rope when the ropes are placed closer to each other by reducing the distance between point s A and B. The weight W remains unchanged. [1]

6 A3 Jonathan applies a vertical force F on a pedal of his bicycle, as shown in Fig. A3.1. Fig. A3.1 (a) As he travels along, the pedal moves through a circle of radius 8.0 cm. For the pedal in the position as shown in Fig. A3.1, the line of action of the force, F is 5.0 cm from the pivot. Calculate the moment of force, F, about the pivot when F = 120 N. [2] F = 120 N

7 (b) Subsequently, the pedal now moves from position A to position B as shown in Fig. A3.1. Explain why the same force of 120 N applied at A will have a different turning effect from the same force applied at B. Show calculations to justify your answer. [3] (c) Jonathan and Tony are cycling at the same speed. The combined mass of Johnathan and his bicycle is 100 kg while the combined mass of Tony and his bicycle is 120 kg. Both decided to stop for a break. Who do you think will find it more difficult to stop? Why? [2]

8 A4 Fig. A4.1 shows a slide in a playground. A boy of mass 35.0 kg climbs up from the side AB in 10.0 seconds and slides down from B to C. Then he decelerates uniformly in the horizontal section CD to a complete stop. The vertical height of the slide is 5.000 m. The horizontal section CD is 0.500 m above ground level. Fig. A4.1 (a) Find the average power developed by the boy when he climbs up the slide. [2] (b) What is the loss in gravitational potential energy of the boy when he moves from point B to point C? [1] 5.000 m 0.500 m

9 (c) If the work done against friction when he moves from B to C is 1000 J, what is the kinetic energy possessed by the boy at point C? [2] (d) State the energy transformation in the horizontal section CD. [1] (e) The length of the horizontal section CD is 5.0 m. Find the magnitude of friction, assuming that friction is constant. [2]

10 Cold water bath A5 Fig. A5.1 shows two vessels, X and Y, connected by a narrow tube and kept in water baths of temperatures 323 K and 363 K respectively. Compared to vessel Y, vessel X has a larger volume. The vessels contain the same type of gas. Fig. A5.1 (a) Discuss whether the following statements are true or false. (i) After some time, the gases in both vessels X and Y would reach the same equilibrium temperature. [2] (ii) After a long time, the gas pressure in vessel X is smaller than the gas pressure in vessel Y. [2] Vessel X Vessel Y 323 K 363 K Hot water bath