Make a Mini Trebuchet

Trebuchets were used in the Middle Ages as a type of siege engine to throw stones at castle walls. It works in a similar way to a catapult, but it uses a pivot and a counterweight to create the force needed to throw the items

The first thing that you are going to need to do is tape the two paper cups to the cardboard base. You want to leave a gap between the paper cups of about half the length of your straw. 

You are now going to cut a small piece of paper and roll it into a tube around your straw. You are then going to tape it in place. Make sure that it can move freely around the straw. You don’t want to be to tight that it doesn’t move. You can then tape your straw between the two paper cups. 

You can now get your lolly stick and to one side attach your milk bottle top using some double-sided tape to make your basket. On the other side of the stick you are going to tape your battery. The battery is going to act as the counterweight.

You are now going to tape the lolly stick to the paper wrapped around the straw. Make sure that it is attached securely. 

You are now ready to test your trebuchet. Put something in the basket and see how far you can fire it. 

Although similar to a catapult the trebuchet works by converting gravitational potential energy – which you get by raising the counterweight, into kinetic energy.

Remember not to fire your trebuchet at anyone!

You may like to experiment with firing different things from your trebuchet and see if this makes a difference. You could try a cotton wool ball, ping pong ball, ball of paper... 

You could also try and make some adjustments to your trebuchet to see if it can fire longer distances. Does a heavier/ lighter battery/ counterweight make a difference? What happens if you have a longer/ shorter arm? Does the place that you tape the lolly stick make a difference? What happens if it is in the centre/ near the battery/ near the basket?

I hope you have fun with this activity.

The video tutorial for this activity is available on the Surrey Libraries Facebook Page or the Surrey Libraries YouTube Channel