WJEC Physics for AS Level: Revision Workbook

Q11 A ball is thrown through the air. At time t 1 it is travelling with a velocity of 15.0 m s −1 at 30.0° to the horizontal and climbing. At time t 2 its velocity is 20.0 m s −1 at 49.5° to the horizontal and falling. (a) Show that its horizontal and vertical components of velocity at t 1 are 13.0 m s −1 and 7.50 m s −1 upwards, respectively. 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(b) By considering the horizontal and vertical components of velocity at t 2 and your answers to part (a), calculate the change in velocity of the ball between t 1 and t 2 . 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Q12 A ball, travelling at 12 m s −1 , collides with a wall and rebounds at 10 m s −1 at right angles to its original direction. The diagram shows this seen from above. 12 m s −1 10 m s −1 N Calculate the magnitude and direction of the change in velocity. 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Q13 A spring has a spring constant k . This is the force per unit extension needed to stretch the spring and has the unit N m −1 . If an object of mass m is hung from the spring, pulled downwards and released, it oscillates with a period, T . A student cannot remember whether the correct equation for calculating T is: T 4 k m 2 = π , T 4 m k 2 = π , T 4 k m 2 2 = π , or T 4 m k 2 2 = π By considering the units of T , m and k , evaluate whether any of these equations could be correct. 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Section 1 Basic physics | 15 Unit 1 Practice questions