Based on my existing scientific knowledge, I know that this experiment depends on a certain type of energy being converted into another type. When the trolley is raised to the top of the ramp, it gains a certain amount of potential energy – this is converted into kinetic (movement) energy as the trolley moves down the slope. Too see what factors may affect the way the experiment turns out, it may be useful to look at the formula for potential energy.
P.E = mhg (where m=mass, h=height and g=gravity)
I will be investigating, by varying the height the summit of the ramp is raised off the ground, if the average speed has any relation to the height of the ramp.
There will always be smaller forces that could slightly affect the result, such as friction between the ramp and the trolley’s wheels, and air resistance. There is no way I can control any of these factors, but they shouldn’t affect the results so much as to give completely anomalous readings for each experiment.
Planning
When planning my experiment, I will need to take into consideration the following points:
· Safety
· Fair testing
· Equipment
· How many results I will take
Safety
With this straightforward experiment there is not much that needs to be taken into consideration. No harmful substances are being used, neither are flames or solvents, so all-in-all a relatively safe experiment. Obviously we will need to take precautions when increasing the height of the trolley and make sure that the ramp is securely fixed with a clamp stand before the trolley rolls down the ramp. Especially when the trolley reaches high speeds, the likelihood of the clamp stand loosening is increased and this could be potentially harmful. Also at the bottom of the ramp some sort of barrier will need to be placed to prevent damage to the trolley as it hurtles off the edge, or to prevent potential harm to any unsuspecting pedestrian/small animal.
Fair Testing
As with all scientific experiments, only one variable must be altered at one time. All the rest must remain constant to ensure good sensible results. By using present knowledge, I know that the following factors can affect the outcome and must be controlled (with the exception of the height of the ramp as this is the variable that I am considering):
· Height of ramp – as this is included in the formula for potential energy, the height of the ramp should affect the speed of the trolley in some way and I will be modulating this variable in the experiment.
· Mass of trolley – mass is also included in the formula for potential energy and so could affect the speed of the trolley one way or the other. During the experiment we should constrain it simply by not adding any weights to the trolley and always using the same trolley to collect each result.
· Gravity – the last portion of the formula for potential energy is gravity, which will affect the outcome if it is increased or decreased. The way to maintain this factor is to simply stay on the same planet.
