Friction of the ramp. The same ramp should be used throughout and also the same car as different cars will have different surface of wheels affecting the speed.
Another factor to make it a fair test could be air resistance but personally I cannot control this we just have to make sure the same car is used throughout.
Prediction
The experiment is based on the potential energy at the top of the ramp being converted into kinetic energy at the bottom. I predict that the higher the ramp the faster the car will travel down it.
Increase in height of ramp=increase in velocity of trolley
As explained below in the theory
A B C
At point A there is zero speed and no kinetic energy so therefore maximum gravitational potential energy. At B the speed is increasing, gravitational potential energy is converting into kinetic energy there is some energy loss as heat. At C the car is at its fastest with maximum kinetic energy and no gravitational potential energy.
To get as accurate and precise results as possible I am compare my results with someone else that has a similar plan to mine.
Safety
This experiment is quite straightforward there is not much that needs to be taken into consideration. No harmful substances are being used neither are flames so all in all it is a relatively safe experiment. Basically common sense is needed.
Formulas
Speed = distance/time
Kinetic energy = 0.5 mass x (speed) 2
Potential energy = mgh
Work done = force x distance
Results
Graph
Going to stick graph here
Analysis
As you can see from the graph the experiment hasn’t gone quite according to plan. As the results were carried out over a period of two days various problems could have occurred. The friction of the ramp somehow may have changed making the car go faster or slower either way. It may not affect the results much but there could have been more air resistance on the second day.
If each day is looked at separately it shows that the speed increased at each height. The higher the ramp the faster the speed. This can be explained. The higher an object goes the more gravitational potential energy it gains. When the car rolls down its potential energy is converted into kinetic energy and since energy can neither be destroyed or created. Only converted; it will move at a faster speed. So therefore height does affect the speed at which a trolley travels down a ramp.
My prediction was correct as the graph shows that the speed increases when the ramp is raised higher when looked at as two different experiments.
So on overall as an object is lifted to a certain height the chemical energy stored in you is converted into gravitational potential energy. The higher you lift an object he more chemical energy you are using so therefore the object is gaining more potential energy. Potential energy is converted into kinetic energy completely so when the object is released it will move at a faster rate on how it is lifted.
This theory explains the increase in speed, if the results recorded are looked at separately.
Calculations
First of all I am going to calculate the average potential energy at each height.
Potential energy = mgh
The average kinetic energy at each height.
Kinetic energy = 0.5 mass x (speed) 2
I am now going to plot a graph to show the relation between potential energy and kinetic energy.
Graph to stick here.
The graph above on overall shows that as the height increases the potential and kinetic energy increases. As the higher the object is the more energy it gains as you can see on the above graph where it displays potential and kinetic energy. On overall as the height is raised the more kinetic and potential energy is gained.
The higher the object = more energy gained
I am now going to calculate work done.
Work done = force x distance
Work done = 0.2851 x 2m
= 0.5702
From this I am now going to calculate the average power.
Power = work done (J) / Time taken (S)
The graph shows that the power has atyed quite steady at each height it increased from 20cm but then stayed constant.
Evaluation
The evidence I have collected is quite reliable when looked at as two separate experiments. The spread of the results is quite close together and the points on the graph are relatively close to the line of best fit. At each height we had one anomalous result I didn’t include these results on my graph or in the calculations. As these would have made the calculations and results more spread out making the evidence not very reliable. My method and plan was quite reliable and precise so don’t understand why the evidence didn’t turn out as expected. Possible reasons could have been that the friction on the ramp changed over the period of two days. It is a very unlikely but there could have been more air resistance on the second day making the results alter. If I were to conduct this experiment again I would use a ticker timer instead of a stopwatch and also a better material to hold up the ramp. As the stool may have tilted or let the ramp slip to one side. I would also carry out the experiment at once and not over a period of days. I would also have barriers on the ramp so the car doesn’t sway of as this happened a number of times whilst we were doing our experiment we didn’t record these results as the car never traveled a distance of two metres. Using the stool and stopwatch wasn’t quite scientific which means that the results could be slightly bias. The calculations I have produced on overall give the right impression as you can see from the graphs and results produced. Even though my results didn’t turn out quite according to plan I have been able to draw up quite a solid conclusion and got the main idea and feeling of the experiment and what it was all about.
