P.E – Potential energy
Potential Energy is stored energy by an object as a result of the positions of the components of that object. For example, if a ball is held above the ground, the object holding the ball up and the Earth has a certain amount of potential energy; lifting the ball higher increases the amount of potential energy. Other examples of potential energy include a stretched rubber band – once stretched out it has a “potential” of flicking back.
To make it a fair test…
- I’m going to vary the weight and keep all the other affecting factors the same such as the ramp length and height.
- I will do the same test three times and get the average so the results will be more reliable and accurate.
- All of the equipment I am going to use will be the same in each run
Variables
Variables that I could change on this experiment that may affect this investigation:
- Height of ramp
- Weight of (added to) trolley *
- Length of trolley
- Angle of ramp
*I am choosing this variable. Each time I will add 100g weights to the trolley (stuck by sellotape)
These variables will be kept the same to make this a fair investigation:
- Length of trolley
- Angle of ramp
- Length of ramp
- Use the same pieces of equipment each time
- Initial velocity of trolley
If predict that if I double the mass the stopping distance will stay the same. (This will only work up to a certain degree as if the trolley is too heavy then it the friction will be too great)
P.E = mgh
e.g - the height of the trolley at the top of the ramp is at is 0.5m and the trolley has a mass of 5N it is released from the top (gravity = 10).
5*10*0.5 = 25J
This means the car has 25J of energy
Work done = change in energy
Stopping distance = Work done / Frictional force
25 / 5 = 5m
Stopping distance will be 5m
Below I doubled the mass and kept every thing else the same. When you increase the mass the gravitational force pressing the trolley down increases, so the friction increases. If I double the mass the friction will double.
EP = mgh
10*10*0.5 = 50J
Stopping distance = work done / frictional force
50 / 10 = 5m
The stopping distance will be the same, 5m.
I will set my results out like this…
Results:
Evaluation:
In the end I don’t believe that this was a very accurate and fair test.
Factors that I think have corrupted this test:
- The floor is uneven and has crack, stones etc therefore the trolley will not travel straight and will not reach maximum capability.
- The wheels are not perfectly smooth and round, also front wheel was not straight and a little loose.
- The trolley went along the tape several times and as the measuring tape is smoother than the ground it will travel further because there is less friction.
- The wind may also of had an small partition of slowing or speeding up the trolley too.
- At the end of the ramp there was a small bump where the ramp met the floor this will slow the trolley down and waste more time.
Some of these can be prevented but some cannot. So if I did this experiment again I would do it inside on a smooth surface and maybe use a ramp with a slanted end so there wont be as much gap between the ramp + floor.
