A ball bearing is released from the top of the v-shaped runway. When it reaches the bottom of the runway it should roll along the bench at a constant speed. The speed, v, will be found by measuring the time it takes for the ball bearing to travel a distance of 1m, hence the metre rule. To improve accuracy, 3 measurements of speed at each height will be taken. In order to construct a good graph the results of at least 6 different times should be used. Prediction
I predict that by increasing the height of the v-shaped runway, this will increase the amount of gravitational potential energy lost, and increase the amount of kinetic energy gained. This is because with the height increasing, so will the ? Ep because the height is one of the variables used to calculate the potential energy. The kinetic energy will decrease because the average speed decreases (i. e. increased velocity in ball bearing) so if the velocity decreases, so will the kinetic energy.
Evaluation There were a few problems in recording results for this experiment, and if this experiment were to be repeated in future, some alterations would be necessary to make the results more realistic and conform to the expected results. If the ball did not roll along the bench in the right direction, after leaving the runway, it would fall off the bench and another measurement would have to be recorded because if the ball does not roll along the bench, the measurement would be void.
The subject on the stopwatch who was stopping the watch when they felt the ball pass the metre rule may not have been accurate with their reactions or may not have stopped the timer at the correct point of the ball bearing passing the rule. The runway used to roll the ball bearing onto the bench had to be smooth and even i. e. the V must have equal lengths on each side. The smoothness of the runway was vital because had it been a rough runway, sand paper for example, it would have decreased the speed that the ball descended down the runway at, therefore decreasing the time it passed the metre rule and the kinetic energy of the ball bearing.
A smooth runway enables the ball bearing to descend, uninterrupted by friction, and giving fair results. The distance between the two rules (shown on the diagram) could be widened to decrease the risk of the ball hitting either rule placed on the bench. If the ball did hit one of the rules, the ball would decrease in speed and lose kinetic energy as it progressed to the point of where the measurement would be taken.
The reason for keeping the rules close together, however, is to ensure that the ball bearing stays on track and between the rules so it does not roll off the bench and onto the floor, resulting in a void, and having to record that particular measurement again and wasting time in the process. Another possible fault with the recording measurements part of this experiment was that it would have been more efficient and accurate to use a “speedometer” to find the speed at which the ball is travelling at, instead of recording the time it takes to travel a certain distance.
A “speedometer”, presuming it would be electrical and more technological, may produce more accurate results and give a better understanding of how increasing the gravity of an object, in this case a V-shaped runway, actually effects the object being released from it. These are problems, which can be solved if we performed the experiment again, and would perhaps give more accurate results.