Science fair experiment - momentum

I needed to explain the concept of momentum to some kids the other day, and came up with an experiment that would be so easy to adapt to a be a great science fair project. It was also an absolute blast doing it and we ended up trying a whole stack of things - getting bigger and better all the time - in fact we pushed it so far that we broke the "equipment" eventually - oops!

When I say "equipment" - I like to use things that are readily available around the house. It is no use having to try to find things that you would only find in a laboratory when trying to explain science which is all around us. You got to use things that you can get easily. So the equipment I am talking about for the experiment on momentum was my young boy's toy truck, a brick, a plank, a stool, a measuring tape, and a whole lot of imagination...

So to explain momentum briefly - it is the force something has when it is moving. If it bumps into something else, the force that it has will impact the object it bumps into - so think of a moving truck crashing into a stationary car. Yup - the car is definitely going to be impacted.

There are two things that affect how much momentum something has - mass (how heavy it is), and speed. So a 10 ton truck going 100 km/hr is going to have more momentum than the same truck going 5 km/hr. But someone on a bicycle going 100 km/hr is definitely not going to have the same momentum as the truck going at the same speed.

So how did I show this in the experiments I did? I set up the toy truck so that it would move without me having to push it - I put it on a slope made from a brick and a plank. Then I let it go and measured how far it went before stopping.

Next, I added a brick to it, to give it more mass. I let it go down the slope again and measured the distance it traveled. Hey presto -it went further. This is because it had more momentum.

So then we added some gradient to the slope to give more speed to the truck. Again it was discovered that more speed means more momentum.

And then we let our imaginations go wild ... more slope, more weight, putting something in front of the truck to see how far it can push it etc. Needless to say I ended up having to repair the toy truck that evening!!

I guess it was all worth it for the fun we had - and we ended up learning a whole lot about momentum.