One. Hi, I’m Nick
from Design Squad Global. We’re at the Acera School,
and we’re building catapults. (drilling) Catapults are really cool. For example, you could throw
a tuna fish sandwich to your friend who doesn’t have
one who could be very far away. You could also use a catapult
to fling snowballs when you’re having
a snowball fight. You would totally win. We’re making our catapults
out of wood, paracord, bungee, and really anything else we can
find around the wood shop. Most catapults use levers. When the lever is pulled back, it gets loaded
with potential energy. When the lever is released,
the potential energy is converted to kinetic energy,
which is the energy of motion. Most of this kinetic energy
goes then into the object– in our case, a ball– which then
gets hurled through the air. We’re going to see whose team can fling a tennis ball
the farthest. And I don’t want
to give anything away, but it’s going to be my team. So the kind of catapult
that we’re working on is this big slingshot that’s
kind of like a triangular shape. Instead of using rubber bands,
we are using bungees. And when you pull back and
let go, it’ll shoot forwards, and we’re going to use
a tennis ball and see how far that can go. So the reason why we’re lashing
the wood together, which is kind of like
tying the wood, is because it will not ruin
the wood so we can reuse it in later projects,
and it won’t cut the wood or put holes in the wood,
and it’s easy to put together and take apart. – The kind of catapult
we’re working on is called a trebuchet. It uses gravity to launch
the tennis ball. We’re redesigning a trebuchet
that I had made last year with some middle schoolers. Now we’re basically
goes into that pole up there. When we release it, the short
part of the lever goes down, the long end of the lever
goes up, pulling this pouch and ball
along the track. And as the arm
gets to a certain point, the ball will be thrown
out that way. (drilling) Yeah! So the initial design had a pail
hanging with rocks for the counterweight. This year, we’ve redesigned it
to have this bar that holds barbell weights. Our old boom pole was five feet,
11 inches. Our new boom pole
is over ten feet. – Wait, I have an idea. This is a really good idea.
I’m feeling it. – So right now we’re trying
to figure out how to attach the can to the bungee cord. – Let go. (laughing) Okay, hold on, here. The problem right now is that
the can keeps turning around, and we can’t keep it straight, so the ball keeps flying
backwards, and that’s a problem. – So because the can was
bouncing around a bunch before, we decided to add
some metal pipes to string the bungee through
to stabilize it. All right, let’s try it. That was not good. – No. We got to figure something else
out because this is not working. Okay, here’s our first test,
just to make sure it works. – Three, two, one! – It works! – It actually works.
– Yes! – It worked better than
I thought it was going to. The tennis ball went pretty far. Now we’re going to add
some more weight, and maybe it will make it
fling farther. More weight, more potential
energy, more kinetic energy. We tried using the tin can
to hold the tennis ball, but it really didn’t work. So now we’re using
a leather pocket to hold the tennis ball instead. – Hopefully this leather pouch
will work better than the can. – First test. – Wow. – Much better. Okay, we’re all set up. It’s slingshot versus trebuchet
and slingshot’s going to win. The trebuchet is going
to destroy that slingshot. Go Team Slingshot! Go Team Trebuchet! Okay, here we go,
we’re going first. Three, two, one, lift it up. Whoo. Three, two, one. So I guess you could say
team trebuchet won because theirs landed farther. If I could make this again
to make it better, I would have it so that
my slingshot can go further to the ground
so that it gets more air. If we could build this again
or improve it, I think we would add more weight so that there would be more
counterweight, so it could go way farther. (cheering, laughing)

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