Acceleration Due To Gravity
Check us out at http://www.tutorvista.com//videos Our equipment consists of small metal ball, which is our free falling object. This ball is held in a clamp which is released by a thumscrew. Initially the ball is held in the clamp and completes an electrical circuit which is connected to an electronic timer. When the thumbscrew is released, the clamp springs open, releasing the ball and opening the circuit, causing the timer to start. A metal pad is placed directly under the ball and when the ball strikes this pad, the timer stops and the elapsed time is read. The clamp which initially holds the ball can be adjusted to varying heights above the metal pad on the floor. For this experiment we positioned the clamp at 7 different heights and released the ball 5 times for each height, recording the elapsed times. The height of free fall was measured with a meter stick from the bottom of the clamped ball to the metal pad with an accuracy of 0.5mm. During the course of the experiment, we noticed several problems with the equipment that could result in systematic errors. First of all, the release contact was not very reliable, causing the timer to begin slightly before ball entered free fall. This would result in longer elapsed times and therefore, smaller values for g. Secondly, the contact plate on the detection pad was not parallel to the floor. The consequence of this is a random deviation of the elapsed time, depending on how high above the floor the ball made contact with the plate. We were able to minimize the effect of the timer starting early by placing a stiffer spring in the clamp and throwing out elapsed times which deviated by more than 0.2s from the average. This does not completely eliminate the problem but does throw out the trials which clearly had problems during release. The second effect was minimized by carefully sighting vertically from the clamp to the plate and making sure that the location of the plate was consistent from trial to trial. A consistent release was obtained by holding the clamp steady with both hands whicle releasing the thumbscrew. This minimized the horizontal velocity of the ball and resulted in a more consistent position of the ball on the metal pad.