The following factors should make the experiment a fair test and eliminate any anomalies:
Factors to control:
The weight
The gradient of the ramp
The trolley
The person timing
The person releasing the trolley and the weight
Factors to vary:
The force (weight on pulley)
The distance
Prediction:
I predict that as the weight on the end of the string is doubled, the time taken is halved across a certain distance. Also, as the distance increases, so will the time taken. Also as the weight increases, so will the speed. This due to as the weight is increased, so is the force pulling the car (GPE). I came to this prediction after looking at some of Isaac Newton’s theories on gravity and forces.
Analysing evidence and drawing conclusions:
The graphs I have drawn clearly show that as the distance the trolley has to travel is increased, so is the time taken.
The graph drawn for 15g shows that the time taken decreases steadily as the distance is decreased.
The graph could not be drawn for 20g as in some cases, the trolley did not move.
The graph for 30g shows clearly shows that as the distance increases the time taken gradually increases.
The graph for 40g shows clearly shows that as the distance increases the time taken gradually increases.
The graph for 50g shows clearly shows that as the distance increases the time taken gradually increases.
The time v velocity graph for 15g shows a steady increase in speed (acceleration) as the force of gravity pulls on the weight and adds more and more force.
The time v velocity graph for 20g shows an increase in speed but then the acceleration increases less dramatically as it gets closer to terminal velocity.
The time v velocity graph for 30g shows an increase in speed but then the acceleration increases less dramatically as it gets closer to terminal velocity.
The time v velocity graph for 40g shows an increase in speed but then the acceleration increases less dramatically as it gets closer to terminal velocity.
The time v velocity graph for 50g shows an increase in speed but then the acceleration increases less dramatically as it gets closer to terminal velocity.
In conclusion, as the weight is increased, the time taken for the trolley to reach a certain distance is decrease. As the weight is increased the trolley will accelerate more quickly but then the increase in acceleration starts to be less dramatic as the trolley gets closer to achieving terminal velocity.
Evaluating:
The experiment went very well and produced some good results that enabled me to draw conclusions and comment on them. Also there were not too many anomalies in the results but had the experiment been done again, I would have tried to obtain less anomalies. I could have timed each run more times and calculate an average to make the test even more fair. We could have used a card and light gate instead of an inaccurate human timing when the trolley crosses the line. We could also have used a data logger to eradicate human error. We could have also done the experiment with more loads to draw more graphs and investigate even further. On the whole, the experiment went well, producing some good results. Also, most importantly, the experiment went safely.
