2022 RSS Phy Prelims P2

1 Riverside Secondary School 6091/02/4E/PRELIM/2022 [Turn over RIVERSIDE SECONDARY SCHOOL SUBJECT : Physics SUBJECT CODE & PAPER : 6091/02 LEVEL/STREAM : 4 Express DURATION : 1 hour 45 minutes READ THESE INSTRUCTIONS FIRST Write your name, index number and class on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A Answer all questions. Section B Answer all questions. Question 11 has a choice of parts to answer. Candidates are reminded that all quantitative answers should include appropriate units. The use of an approved scientific calculator is expected, where appropriate. Candidates are advised to show all their working in a clear and orderly manner, as more marks are awarded for sound use of Physics than for correct answers. At the end of the examination, submit Section A and B separately. The number of marks is given in brackets [ ] at the end of each question or part question. __________________________________________________________________________ This document consists of 24 printed pages. Section A NAME: NO: CLASS: PRELIMINARY EXAMINATION 2022

2 Riverside Secondary School 6091/02/4E/PRELIM/2022 [Turn over Section A Answer all the questions in this section. 1 (a) An athlete uses an exercise machine, as shown in Fig. 1.1. Fig.6.1 The athlete moves backwards and forwards along the track. As he pulls the handle, he moves backwards and the machine displays the force exerted by the athlete. At the end of the track he stops pulling and then returns to the position shown. This is one complete movement. (a) An accurate value for the average time for one complete movement is obtained. Describe what measurements are taken and how they are used to find the average time for one complete movement. ………………………………………………………………………………...………….…… ………………………………………………………………………………...………….…… ………………………………………………………………………………...…………….… ………………………………………………………………………………...………….…… ………………………………………………………………………………...………….…… ………………………………………………………………………………...………….…… ………………………………………………………………………………...……….……… …………………………………………………………………………..……………..….. [3] (b) A student wants to calculate the average power input to the machine by the athlete. Apart from the measurement in (a) and the average force exerted, state the other measurement that is needed. ………………………………………………………………………………………………… …………………………………………………………………………………….………. [1] 2 A train of mass 1.8 x 105 kg is at rest in a station. At time t = 0, the train begins to accelerate Fig. 1.1 track exercise machine

3 Riverside Secondary School 6091/02/4E/PRELIM/2022 [Turn over non-uniformly along a straight, horizontal track and reaches a speed of 20 m/s at t = 15 s. The train continues at a speed of 20 m/s for 10 s. At t = 25 s, the driver applies the brakes and the resistive force on the train causes it to decelerate uniformly to rest in further 24 s. Fig. 2.1 is an incomplete distance-time graph for the journey. (a) Complete Fig. 2.1 by drawing (i) a curve to represent the motion of the train between t = 0 and t = 15 s (ii) a line to represent the motion of the train between t = 15 s and t = 25 s. [2] (b) Calculate the kinetic energy of the train between t = 15 s and t = 25 s. kinetic energy = ……..……………… [2] (c) While the train decelerates to rest, it does work against the resistive force and its kinetic energy decreases.

4 Riverside Secondary School 6091/02/4E/PRELIM/2022 [Turn over (i) Define work done. ……………………………………………………………………………...……..…… ………………………………………………………………………………....…… [1] (ii) Using Fig. 2.1, determine the distance moved by the train while it decelerates. distance = ……..………………[1] (iii) Calculate the resultant force acting on the train while it decelerates. resultant force = ……..………………[2] 3 (a) Fig. 3.1 shows a piece of glass of thickness 2.0 cm and area 0.15 m2. The density of the glass is 2.6 x 103 kg/m3.

5 Riverside Secondary School 6091/02/4E/PRELIM/2022 [Turn over The gravitational field strength g is 10 N/kg. (i) Explain what is meant by the weight of an object. ………………………………………………………………………..………………… ………………………………………………………………………..…….………. [1] (ii) Calculate the weight of the glass. weight of glass = ……..………………[2] (b) The piece of glass shown in Fig. 3.1 is used as the vertical viewing window of an aquarium. The atmospheric pressure outside the aquarium is 1.0 x 10 5 Pa. The average pressure on the inside of the aquarium window is 1.3 x 105 Pa. Calculate the resultant force acting on the window due to these pressures and state the direction in which it acts. force = ……..………………[2] direction of force = ……..………………[1] (c) Fig. 3.2 shows a vacuum pump connected to the top of a vertical tube with its lower end immersed in a tank of liquid. The pump reduces the pressure above the column to zero and the pressure at point X is 9.6 x 104 Pa. area 0.15 m2

6 Riverside Secondary School 6091/02/4E/PRELIM/2022 [Turn over The gravitational field strength g is 10 N/kg. Calculate the density of the liquid. density of liquid = ……..………………[2] 4 Fig. 4.1 shows a door and an automatic door-closer viewed from above.

7 Riverside Secondary School 6091/02/4E/PRELIM/2022 [Turn over When the door opens and closes, the hinge acts as a pivot. A girl opens the door by exerting a force P at point X. Force P is perpendicular to the surface of the door. (a) Fig. 4.1 shows that point X is a distance of 0.72 m along the front of the door from the hinge. The force P is 25 N. (i) Calculate the moment of force P about the hinge. moment of force = ……..………………[1] (ii) The door rotates about the hinge by 90⁰. As it rotates, the force P remains perpendicular to the surface of the door. The circumference of a circle of radius 0.72 m is 4.5 m. Calculate the work done on the door by force P. work done = ……..………………[2] (b) As the door opens, there is a force F on the door in the direction shown in Fig. 4.1. Although force F is larger than force P, the door rotates about the hinger. Fig. 4.1 point X bar fixed to wall hinge door closer door bar P F 0.72 m

8 Riverside Secondary School 6091/02/4E/PRELIM/2022 [Turn over Explain why. ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ……………………………………………………………………….…………...……….. [2] 5 A small glass measuring cylinder of oil is placed inside a freezer where the temperature is – 18 ⁰C. Fig. 5.1 shows how the temperature of the oil varies with time t. Fig. 5.1 shows that it takes a shorter time for the temperature to decrease from 20 ⁰C to 10 ⁰C while it takes a longer time to decrease from 0 ⁰C to -10 ⁰C. (a) Suggest why these times are different. ………………………………………………………………………………....……………… ………………………………………………………………………………....……………… …….………………………………………………………….………………………….……. …………………………….……………………………………………………..…………[2] (b) Explain, in terms of molecules, why the temperature of the oil does not change between t = 3600 s and t = 10 800 s. Fig. 5.1 t / s temperature / ⁰C

9 Riverside Secondary School 6091/02/4E/PRELIM/2022 [Turn over ……………………………………………………………………………………..…….…… ……………………………………