* USE THE SAME CAR EACH TIME TO HAVE A FAIR TEST.
There are some factors that I kept the same. In order to keep the experiment fair:
- The plastic car.(because the variety in cars might effect the distance it travels.)
- The same point on the ramp to start the car rolling down .
- The same area to do the experiment.(because the ups and downs on the surface of the ground might increase its friction therefore the speed would decrease.)
- The same ramp each time.
Pre-test:
I have used a science experiment CD Rom to discover these results:
Results:
*Calculations for Kinetic Energy and Potential Energy:
Ke = ½ mass x speed² Mass of the car = 0.0165 kg
Pe = mass x gravity x height
To extend my experiment I’ve chosen 60cm of the ramp to be travelled by the same car and I’ve used the stop watch to measure the time that it takes to travel at the variable heights.
Results:
60 cm = 0.6 m
Analysis:
As my results show , when I set the ramp higher, and put the car on it to roll down it travels the further distance.
When I set the ramp at the height of the 3cm, the car travels 13.08 cm from the end of ramp, but when I set the ramp at the height of 7cm , it travels 64.83 cm from the end of ramp.
That proves that the gravitational potential energy of the car increase as it gets higher of the ground.
I also calculated the potential energy of the car at different heights of the ramp.
My results show the same thing which is, as the car gets higher of the ground it obtains more potential energy. At the height of 10cm the car has 0.0165J of potential energy, and as I calculated its kinetic energy, the answer was 0.0020J , that result shows the car has lost 0.0145J of its potential energy which is the LOSS energy, so the car might lost its potential energy for friction with the ramp and the ground during its travel on the ramp.
As I’ve calculated the time which has been taken by the car at the same distance of 60cm at the ramp, it proves that the car takes less time to travel the distance at the higher height of the ramp.
The car travels 60cm in 0.22 seconds at the height of 10cm of the ramp and it also has more speed which is 0.492m/s , but as the same car travels 60cm at the height of 7cm of the ramp it takes 1.46 second and its speed is 0.411.
That clearly shows as the height of the ramp gets higher it takes the car to travel the same distance faster and with more powerful speed.
Evaluation:
In my experiment I’ve tried to keep my test fairly and accurate, so I’ve kept all the factors the same except my variables factors , and I repeated my recorded results for more than 2 times in order to keep it a fair test but during my experiment I’ve made a mistake in calculating of the time taken by car to travel at the same distance,(because I was using a handy stop watch) at the height of 9cm,the result was anomaly so I had to repeat the experiment.
If I was going to do the experiment once more, I would use a light gate for calculating the time’s been taken by the car to travel the same distance of 60cm. Because that would improve my experiment and it would give me more accurate results.
I would also repeat the experiment more than 4times to obtain more accurate results.
I would also use different cars to obtain a larger range of results and I could compare them to each other to find out the effect of gravitational potential energy on different masses.