10 (B420U10-1) Examiner only 5. George attempts to determine the acceleration due to gravity using the following apparatus. The ball bearing starts from rest just above the top beam of light. When the ball bearing cuts the top beam it starts the timer and when it breaks the bottom beam it stops the timer. © WJEC CBAC Ltd. (a) (i) The vertical distance, h, between the two light beams was measured using a metre ruler of resolution 1 cm and was found to be 1.25 m. Determine the percentage uncertainty in this result. [1] 0:00 Light sensor 1 Light sensor 2 Timer Height, h Ball bearing Laser 2 Laser 1 (ii) The time, t, taken to fall through the distance, h, was measured three times and the following results were obtained. Time 1 / s Time 2 / s Time 3 / s 0.51 0.53 0.50 Determine the mean time taken for the ball bearing to fall along with its percentage uncertainty. [2] (B420U10-1) Turn over. 11 Examiner only © WJEC CBAC Ltd. (iii) Use the equation: gt2 2 to determine a value for the acceleration due to gravity along with its absolute uncertainty. [4] (iv) State why the value you obtained in (a)(iii) is less than 9.81 m s–2. [1] (b) (i) Annabel suggests that the experiment would be more accurate if times were obtained for the ball bearing to fall different vertical distances and a graph was drawn. Do you believe Annabel is correct? Justify your answer. [2] (ii) Explain which graph should be drawn to determine g and how it can be used to find a value for g. [2] 12 h = 12 (B420U10-1) Examiner only 6. (a) Explain, with the aid of a diagram, what is meant by the moment of a force about a point. [2] (b) © WJEC CBAC Ltd. pivot uniform metre ruler newtonmeter 95 cm 10 cm (i) A uniform metre ruler is pivoted at the 10 cm mark and the other end is supported by a newtonmeter attached to the 95 cm mark. The ruler balances horizontally when the newtonmeter reads 0.8 N. Determine the mass of the ruler to an appropriate number of significant figures. [3] (B420U10-1) Turn over. 13 Examiner only (ii) A mass of 0.5 kg is now added at the 70 cm mark on the ruler and the ruler is adjusted to be horizontal once more. I. How could you check the ruler is horizontal? [1] II. What is the new reading on the newtonmeter when the ruler is horizontal? [2] (c) If a uniform metre ruler of greater mass than the one in part (b) were used, describe how you could alter the apparatus so the ruler is horizontal once more. Explain your reasoning. [2] © WJEC CBAC Ltd. 10 14 (B420U10-1) Examiner only 7. Louise and Ryan stand a few metres apart on a stationary boat. Louise throws a heavy ball to Ryan who catches it. Describe and explain the motion of the boat from the moment Louise starts to throw the ball until just after the ball is caught by Ryan. Ignore all resistive forces. [6 QER] © WJEC CBAC Ltd. END OF PAPER 6 (B420U10-1) 15 © WJEC CBAC Ltd. BLANK PAGE