In the lab, we would have been doing this experiment
http://wigtonphysics.blogspot.com/2015/02/braking-distance-experiment.html where we roll a trolley down a ramp into a box and measure how far it slides along the floor. The friction between the box and the floor is like the friction on the brakes of a car so it helps us to see how changing the speed affects the braking distance. Here's a version to do at home:
1. Prop your science book or something similar up to the height given in the results table. We are going to be deliberately changing the height so that is the independent variable.
The independent variable is the one that you can write into the results table before you start. The independent variable is usually on the left hand side of the results table.
2. Hold a pen about 0.5 cm above the top of your book ramp and gently drop it onto the ramp.
3. It will roll down the ramp. Try to get it to roll straight. If it rolls off to one side, do it again.
4. Let it roll onto the floor - carpet is best. Measure how far it goes from the bottom of your book until it stops.
5. Repeat 3 times for each height of the ramp.
6. Remember that the RANGE of the repeat readings for each height is (biggest repeat - smallest repeat)
7. Finally, the uncertainty = 1/2 x range of repeats
