Year 10 rolling tin distance-time graph experiment

For this experiment you need a board or a hard-backed book. You need to prop up your book. I propped it up on an exercise step. Then I measured 50 cm along the floor from the bottom of the book and put string on the floor to mark the finishing point. You don't have to use string - you could mark it with something else.

 I got a full food tin and released it from the top of the ramp so that it could roll down.

I started my stopwatch when the tin reached the floor at the bottom of the ramp. I was timing the tin as it rolled along the floor towards the string.

I got into position so that I could see exactly when the middle of the tin crossed the string. I stopped my stopwatch when this happened. If I hadn't got in position to look down on the tin crossing the string there would have been a parallax error.

I did two more repeat readings for 50 cm and calculated the mean. Then I moved the string to 75 cm from the bottom of the book and did the experiment. Then the string moved to 100 cm and so on. Each time I was deliberately changing the distance that the tin was rolling. Here is what the results table looks like:

This is what my distance-time graph looked like:

You can tell that the tin slowed down because the line startes steep and then is less steep at the end. The gradient of a distance-time graph tells you the speed.