RP3-Determination of g

• Equipment: Stand, clamp, light gates, stopwatch, ball.
• Set up: Position the light gates vertically above each other on the stand, and connect to the stopwatch. The stand should be clamped down.
• Method: Measure the distance between the light gates. Drop the ball between them and record the time taken. Move the light gates closer together or further apart and repeat.
• Graph: Plot a graph of two times the distance between the light gates against time. The gradient is g.
• Analysis: s = ut + 1/2 g t^2. The y intercept is 2 u, where u is the speed of the ball when it passes the top light gate.
• Safety: Stand could topple - use a clamp or counterweight; ball could hit something - use a padded tray to catch it.
• Alternative experiments: Use an electromagnet and steel ball to ensure the ball is released from the same height and position each time.