Answers to End-of-chapter questions 3 Dynamics – explaining motion 1 a 6440 ≈ 6400 N b 656 ≈ 660 kg 2 a 112 N b 388 N c 5.54 m s−2 3 a At first the only force is the weight but as its speed increases viscous drag increases. When viscous drag equals weight the acceleration is zero and the speed is constant. b Put rubber bands around the cylinder the same vertical distance apart along the cylinder. Time the ball between the bands. When terminal velocity is reached the time taken between successive bands will be constant. 4 a 6 × 10−4 m s−1 b 2 × 10−3 m s−1 c 2 × 10−3 m s−1 5 a i The Earth, ii upwards, iii gravitational force b i The Earth or the ground under the man, ii downwards, iii contact force AS and A Level Physics © Cambridge University Press Chapter 3: Answers to End-of-chapter Study questions skills 1