Dead on target.
Yes!
This is a simple toy cannon that's easy to make.
My boys have had loads of fun playing with it. I'll explain how to make it
in a moment, but the thing I love about it
is the fact that it allows children to explore energy,
forces, and motion all while making something.
You can fire different things out of it. You can control how much
you pull the rubber bands back. You can change the angle.
In other words you can explore projectile motion,
the way in which things fly through the air.
To make one of these cannons, you need to start by cutting off the bottom
of one of these crisp tins. So we'll take the scissors
and push them through.
You'll probably want to do this yourself because it's a little tricky
We cut it right the way around.
Next you want to cut two slits
up close to the top first on one side,
and then on the other. What these are going to do
is provide the attachment point for your rubber bands.
So here go two rubber bands: one on one side,
and one on the other side like this.
Then, with some masking tape you can secure
the rubber band in place and strengthen
the top of the can.
So here we are, ready to go, and now tear that off.
So the whole thing
is ready and in place. We can set that aside
and now we're going to take a bottle.
Again we're going to use scissors
to poke a little hole in the bottle like that
and the same thing on the opposite side.
Again you want to be a little careful with the scissors.
With that in place we're now going to take a pencil
and push that through the two holes.
Force it through, and now our bottle is ready.
We can assemble the entire device by putting this plunger
in and securing it with
the two rubber bands.
Our cannon is now made and ready to fire.
You can use any projectile you want and I've got a variety of balls here.
But of course if you're playing inside I suggest you use
these scrunched up balls of tinfoil. You can drop them in
and using these you can actually minimize the amount wreckage
that you're going to cause
in your house.
Okay let me try with this: whoops!
Oops, missed! Yay!
The cannon is a simple device to transfer energy from one thing
to another.
When I pull the bottle back, energy from me
is stored in the rubber bands. When I release the bottle
that energy is transferred into the movement of the projectile,
in other words into kinetic energy.
Why don't we make a stack of stuff, where you have to try to knock everything down?
Simply asking a few questions while you're doing this activity
might help you and your kids get a little bit more out of it.
What do you think makes for the best catapult?
Maybe the one that goes furthest?
And one that goes highest?
But actually highest is really hard to measure...
So what is the tennis ball doing?
It's heavy, and it's just dropping.
So what does that mean, if it's really heavy? What happens?
It doesn't go high. It just goes up like that.
I like this activity because it's quite fun
and it's kind of cool when you have to go back and
remake your catapult and and make it better and better,
and see how it goes once you've done it.
I think they're easy to make,
they fire really well, and I think we should get them
into my school.