TE Enriched Sample (E)

Orbital Motions under Gravity 3 92 A. g-force time / s 0 0 5 10 B. g-force time / s 0 0 5 10 C. g-force time / s 0 0 5 10 D. g-force time / s 0 0 5 10 13. NSW HSC 2012 The graph shows how the gravitational potential energy ( E p ) of a satellite changes with its altitude. −10 −9 −8 −7 −6 −5 −4 −3 −2 −1 0 5000 10000 15000 20000 altitude (km) E P (10 9 J) What is the change in gravitational potential energy of the satellite when its altitude is reduced from 14 000 km to 4000 km? A. −8.8 × 10 9 J B. −2.8 × 10 9 J C. 2.8 × 10 9 J D. 8.8 × 10 9 J 14. HKDSE 2012 An interplanetary spacecraft is launched from the Earth. The initial speed is R GM 3 , where G is the universal gravitational constant, M is the mass of the Earth and R is the radius of the Earth. What is the speed of the spacecraft when it is very far away from the Earth? A. R GM B. R GM 2 C. R GM 2 D. zero 15. HKDSE 2012 Which statement about the motion of the Earth around the Sun is incorrect? A. The speed of the Earth in its orbit is not constant. B. The Sun is at the centre of the Earth's orbit. C. The distance from the Sun to the Earth changes periodically. D. In general, the instantaneous velocity of the Earth is not perpendicular to the Sun's gravitational force. 8. The escape speed of the Earth is higher than that of the Moon because A. the Earth has a larger mass. B. the Earth has a larger radius. C. the Earth has an atmosphere. D. the Moon is orbiting the Earth. 9. An astronaut experiences weightlessness inside an orbiting spacecraft. He can float around in it. The astronaut and the spacecraft must have the same (1) acceleration. (2) speed. (3) momentum. A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only 10. An astronaut appears to be weightless inside a spacecraft orbiting around the Earth. Which statement is correct? A. The gravitational field strength produced by the Earth at the position of the astronaut is almost zero. B. The gravitational forces from the Earth and from the Moon cancel each other out. C. The centripetal force of the spacecraft and the contents inside cancel out the total weight. D. Both the spacecraft and the astronaut are falling freely towards the Earth. 11. AQA A-level PHYA4/1 Jan 2011 As a comet orbits the Sun the distance between the comet and the Sun continually changes. As the comet moves towards the Sun this distance reaches a minimum value. Which one of the following statements is incorrect as the comet approaches this minimum distance? A. The potential energy of the comet increases. B. The gravitational force acting on the comet increases. C. The direction of the gravitational force acting on the comet changes. D. The kinetic energy of the comet increases. 12. NSW HSC 2011 A rocket is launched. Its engine produces a constant thrust for the first 10 seconds and is then switched off. Which graph best illustrates the g -force experienced by an astronaut in the rocket? [Editor’s note: g -force is a measurement of all kinds of accelerations that cause weight] B (30%) (43%) (3.1) Q1.5 A (26%) (35%) (3.3) Q1.2 B (3.3) section I Q4 A (3.4) section I Q8 A (3.3) Q12 D (3.4) Modified from DSE 2012 Q1.1 A (3.4) A (3.3) Modified from IB HP1 May 2001 Q10 Sample © United Prime Educational Publishing (HK) Limited, Pearson Education Asia Limited 2023 All rights reserved; no part of this publication may be reproduced, photocopied, recorded or otherwise, without the prior written permission of the Publishers.