Safety
- I would make sure that no one would step onto the ball.
- I would also use the equipment correctly and sensibly.
Range and Other Key Factors
I would be changing the height of the ramp by 5cms every time. I have chosen this range because I think that if I change the height of the ramp by 10cm every time, I would not get very consistent results, and so it would lead to a very spaced out graph. It would then be hard to see how the height of the ramp affects the stopping distance.
Other key factors that would change the stopping distance of a ball rolling down a ramp could be the: friction caused by the surface the ball is rolling on to, the mass of the ball, speed of the ball, the surface area of the ball, the material of the ball and the surface of the ramp.
I will be only investigating the affect of changing the height if the ramp.
Prediction
I predict that the higher the ramp is, the longer the stopping distance of the ball would be.
I think this because the higher the ramp is, the more potential energy the ball would have. The potential energy will turn into kinetic energy as it rolls down the ramp. When the ball is stopping, the carpet’s friction would be acting upon the ball. However, not all the potential energy is transferred to kinetic because some if the energy is lost to becoming sound and also heat caused by the friction.
The stopping force on the ball would be the work done by the carpet (force x distance).
We know that mgh=fd, because the force, mass and gravitational pull are all constant and if we vary the height, then the distance would also have to change to make the equation balanced with the other.
Analysis
During the experiment I saw that the higher the ramp the longer it took for the ball to stop. I then recorded my results and drew a graph.
We can see from the best-fit line of the graph, that the stopping distance is directly proportional to the height of the ramp.
However if we look at the points themselves rather than the best-fit line, we can see that the last three points (45cm, 50cm, 55cm) are slightly to the right more. This is because if the ramp is too high, the ball had started to bounce when it rolled down the ramp, and so it’s stopping distance was affected.
We know that as the ramp is higher the more potential energy the ball would have. This energy is then turned into kinetic energy as it rolls down the ramp. However some of the potential energy is lost in the form of sound and also to the heat caused by the friction with the carpet. This is why the points on the graph are not all in a straight line and the conclusion that I have drawn is only form looking at the best-fit line.
From looking at the best-fit line and seeing that the stopping distance is directly proportional to the height of the ramp it proves that the work done by the carpet to stop the ball is equal to the gravitational potential energy of the ball.
I can say that my prediction is correct and that it is true to say the higher the ramp, the longer the stopping distance would be.
Evaluation
I think my results are reliable enough to draw a conclusion from as it produces a graph where we can see that the stopping distance is directly proportional to the height of the ramp.
However I do think that I could have improved the experiment to achieve more accurate results by measuring in mm. This would give me a very accurate reading of the stopping distance. I could have also used the same ball. This would have improved the experiment as it would make it a fair test and also if I used different balls, then it might have a different mass or surface area. I could have also repeated the experiment a few more times so that I could have a better average.
From the graph I can see a few anomalous points. This might be because there might have been a bump in the carpet or even a different ball. I would not necessarily say that the last three points of the graph are anomalous because of an error but it is because the ball might have bounced as it rolled down the ramp, as the ramp is higher.
I would have extended the investigation by investigating other factors that would affect the stopping distance of a ball rolling down a ramp such as the angle of the amp, the mass of the ball, surface of the ball and/or the surface it is rolling on to.