RI 2023 Y5 Phy T3 CT Sect B QP

© Raffles Institution 9749 Name: ( ) CT Group: 24S0 RAFFLES INSTITUTION 2023 YEAR 5 TERM 3 COMMON TEST 4 July 2023 H2 PHYSICS RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES Section B INSTRUCTIONS TO CANDIDATES Write your name, index number and CT Group. Write your answers to Section B in the spaces provided on the question paper. You are advised to write all your workings and answers clearly. Marks may be deducted for unclear workings. For Examiner’s Use Section A MCQ / 14 Section B 1 / 10 2 / 10 3 / 11 4 / 13 5 / 9 6 / 7 7 / 11 Deductions Total / 85 This document consists of 19 printed pages.

2 © Raffles Institution 9749 [Turn over Section B (71 marks) 1 The resistance R of a wire is related to its length L and cross-sectional area A by the equation LR Aρ= where ρ is the resistivity of the material that the wire is made of. To determine the resistivity of the material of a wire, a student needs to first determine the resistance of the wire. He sets up an electrical circuit to measure the potential difference V across the wire and the current I through the wire and calculates the resistance R of the wire using VR = I . He also measured the length L and the diameter d of the wire using a meter rule and a micrometer screw gauge, respectively. (a) While measuring the diameter, the student failed to notice that the micrometer screw gauge reading is not zero when it is fully closed. State and explain whether this introduces random error or systematic error to t he measurements of the diameter. [2] (b) The student eventually realised his mistake and accounted for the zero error in his measurements. The average values of all quantities, with their uncertainties, are shown in Fig. 1.1. V / V I / A d / mm L / cm 1.50 0.01± 0.32 0.01± 0.23 0.01± 40.0 0.1± Fig. 1.1 (i) Calculate the value of ρ . ρ = mΩ [3]

3 © Raffles Institution 9749 [Turn over (ii) Calculate the uncertainty in ρ . uncertainty in ρ = mΩ [2] (iii) Express the value of ρ together with its uncertainty to the appropriate number of significant figures. ρ = ± mΩ [1] (c) The true value for ρ is 74.4 10 m−×Ω . Use your answer in (b)(iii) to distinguish between accuracy and precision. accuracy precision [2]

4 © Raffles Institution 9749 [Turn over 2 (a) A fighter jet approaches a stationary tank at a speed of 1220 m s− and at an angle of 15° below the horizontal as shown in Fig. 2.1. A bomb is released from the fighter jet when it is at a height of 800 m above the ground and 1500 m away from the tank. Assume that air resistance is negligible. Fig. 2.1 (i) After the bomb falls through a vertical distance of 800 m, 1. calculate the time elapsed from when it was released, time = s [2] 2. determine the magnitude and direction of its velocity. magnitude = 1m s− direction = [3] 800 m 1500 m 15° tank fighter jet

5 © Raffles Institution 9749 [Turn over (ii) Explain, with appropriate calculations, whether the bomb will hit the tank. [2] (iii) On Fig. 2.2, sketch the variation with time t of the vertical displacement ys of the bomb from the point of release for the duration in (a)(i)1. Take downwards direction as positive. Fig. 2.2 [1] (b) Two projectiles are launched simultaneously from the same point to hit targets A and B. Fig. 2.3 shows the path of each projectile . Both projectiles reach the same maximum height before hitting their respective targets A and B. Fig. 2.3 Explain whether the projectiles hit their respective targets at the same time. [2] launch point target A target B / m t / s 0

6 © Raffles Institution 9749 [Turn over 3 (a) Distinguish between the mass and weight of a body. [2] (b) Explain why a passenger sometimes feels lighter in a lift. [2] (c) Fig. 3.1 shows a pile driver of mass 800 kg which is released from rest and falls vertically through a height of 5.0 m before striking a pile of mass 200 kg. The pile then penetrates vertically into the soil. The average soil resistance on the pile is 450 kN. Fig. 3.1 Assuming that air resistance is negligible and that the pile driver moves together with the pile after striking it, calculate (i) the velocity 1v of the pile driver just before impact with the pile, 1v = 1m s− [2] soil pile driver pile ground 5.0 m

7 © Raffles Institution 9749 [Turn over (ii) the velocity 2v of the pile just after impact, 2v = 1m s− [2] (iii) the penetration depth of the pile into the soil. penetration depth = m [3]

8 © Raffles Institution 9749 [Turn over 4 A street sign is in the shape of an equilateral triangle of side length L and mass 2.5 kg. Its centre of gravity, O, is at the centroid of the triangle. The centroid of the equilateral triangle is the point of intersection of the perpendicular bisectors of the sides of the triangle and is equidistant from each of the vertices A, B and C as shown in Fig. 4.1. Fig. 4.1 (a) The street sign is hung from the ceiling by two vertical light cables attached to A and C such that side AB is vertical, as shown in Fig. 4.2. Fig. 4.2 (i) State what is meant by centre of gravity. [1] (ii) State the principle of moments. [1] O L A B C O T1 T2 A B C ceiling cables

9 © Raffles Institution 9749 [Turn over (iii) Determine the tensions T1 and T2 in the two cables. Show your working clearly. T1 = N T2 = N [4] (iv) To reduce the tension in the cable attached to vertex A, with the street sign hung in the same orientation as before, the cables could be attached in a slanted manner as sho