# MEDIEVAL ENGINEERS: THE SCIENCE BEHIND THE CATAPULT

A
catapult is a lever, a stick or beam, propped up by a fulcrum, the pivot point.
The catapult magnifies your force to throw an object. So, you do not need as big
of a force to propel a large object, but the larger the force, the farther it
goes. In ancient times, catapults were used to throw heavy rocks.

Levers
and fulcrums can be used to pick up heavy things like rocks and building
materials. Have you ever used a see-saw? That’s a lever and fulcrum! See if you
can point out which part of your catapult is the lever, and which is the
fulcrum? The craft stick with the spoon is the lever and the stack of other
craft sticks is the fulcrum. The spoon beam pivots around the stack to generate
the force to launch the load. When you press down on the spoon, it pulls up on
the rubber band on the opposite end—this is its potential energy. When the
spoon is released, it pulls back up on the rubber band and the pom pom goes flying!
The potential energy is converted into energy of motion- kinetic energy.
Gravity also does its part as it pulls the object back down to the ground.

Take
it Further:

Try
launching a bouncy ball with your catapult. Compare it with the pom pom. How far
or high did it travel? Did it go as high or far as the catapult?

The
catapult also demonstrates Newton’s 3 Laws of motion:

An object at rest stays at rest until a force is applied, and an object will stay in motion until something creates an imbalance in the motion. (First Law) The acceleration produced when a force is applied depends on the mass of the object. (F = Ma; Second Law) Every action causes an equal and opposite reaction. (Third Law)

The
pom pom will remain at rest until a force acts on it (the release of the spoon
and/or gravity) – First Law

The
bouncy ball will not travel as high or far as the pom pom as the bouncy ball
has more mass than the pom pom and will require a larger force to travel the
same distance and speed as the pom pom – Second Law (Force = Mass X
Acceleration)

When
the spoon is pushed down, the load (pom pom or bouncy ball) travels upward- in
the opposite direction equal to the force applied on it. (Third Law of
Action-Reaction)

A catapult is a simple machine that has been around for ages. Have your kids dig up a little history and research when the first catapults were invented and used! Hint; check out the 17th century!

Join our HTHT @ Home Science Experiment to make your own Catapult: https://sciencemadefun.net/downloads/Catapult_EOTD_May%206th.pdf

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