Build

Instructions

• 1

Here are some of the materials you can use

• balls (Ping-Pong, golf)
• brass fasteners
• corrugated cardboard sheet (corrugated cardboard has grooves in the middle, like a cardboard shipping box)
• paint stirrers (found at paint supply or hardware stores)
• paper clips
• paper cups
• popsicle sticks
• rubber bands
• ruler
• scissors
• string
• tape (masking or duct)
• wooden skewers or dowels
• 2

Prepare ahead of time

• Have paper and a pencil ready to write down ideas and sketches as you design.
• Think about devices that people use that move balls. (Pinball machines, baseball or tennis ball throwing machines) What power source do they use?
• 3

Think about the challenge

• A pendulum is a rod with a weight at the end of it that allows it to swing back and forth. What kinds of machines have a pendulum swing? (Amusement park rides, clocks, swings)
• How can a pendulum move a ball? How can a rubber band move a ball?
• How will you stop the ball from launching before you’re ready to release it?
• How will you release the right amount of force needed to launch the ball?
• 4

Think about and write down your ideas

• How does a pendulum or rubber band store energy?
• How can you use gravity to get a ball moving?
• How can a rubber band get a ball moving?
• How will you launch your ball when you are ready to release it?
• TIP: When you lift a pendulum or stretch a rubber band, you increase its stored energy, or its potential energy. When you release the pendulum or rubber band, its potential energy is turned into kinetic energy, the energy of motion. Many machines turn potential energy (such as electricity and muscle power) into kinetic energy.
• TIP: Gravity is a force that acts like a magnet in that it attracts one object to another. Gravity will move an object to the floor if you drop it or hit it with a pendulum.
• 5

Look at the materials

• What will you use to make the base for your launcher?
• What materials do you have to build a release trigger for your machine?
• What materials do you have to build a pendulum launcher? A rubber band launcher?
• What will you use to make sure the ball goes in the right direction?
• TIP: A pendulum device could be a golf ball taped to a string or a piece of cardboard hanging from a frame. A rubber band device could have a rubber band stretched between two posts.
• 6

Design and build the machine base

• Decide what size you will make your kicking machine.
• Think about how big the base for the machine will need to be.
• Think about what materials you will use for the base.
• Choose the materials and build the base.
• TIP: Your base will need to be a smooth surface so the ball does not get stuck or slowed down by ridges or bumps in the base.
• 7

Design and build the launch frame

• Decide what materials you need to make the frame to hold the pendulum or rubber band.
• Choose the materials and build the frame.
• Test that it is strong enough to hold the pendulum swing or the stretched rubber band.
• TIP: If the stretched rubber band bends the frame, try using stronger materials for the frame or make the frame stronger by reinforcing it.
• TIP: You can test a design at different steps along the building process. This way you can spot a problem, such as a bump in the base, and fix it when it happens instead of at the end of the process.
• 8

Modify your base or build a ball holder

• Decide how you will keep the ball from rolling off the base until you release it.
• Think about modifying the base or designing an extra feature to hold the ball.
• Choose the materials and build the ball holder.
• 9

Modify your base or build a ball holder (continued)

• Place the ball in the holder on the kicking machine.
• Modify the design if the ball rolls off.
• TIP: If the ball won’t stay in place, try using a paper clip or a piece of cardboard to anchor it.
• TIP: If the ball rolls out of the holder, try tying a piece of string across the holder, and use it to pull back the rubber band. Then release it.
• 10

Test the kicking machine

• Place a cup on its side 12 inches (30 cm) away from your kicking machine. Tape it down.
• Position the direction of your machine so the ball goes in the cup.
• Release it!
• TIP: If the ball is hard to get into the holder, try using different release points for the pendulum or the rubber band. Or check whether the ball bumps into part of the machine on its way out. If necessary, revise your design.
• TIP: You’ve just built a prototype, which is an early version of a product. Prototypes help engineers understand a product’s strengths and weaknesses and how the product might be improved.
• 11

Did you know?

• Catapult Launch
Devices have been used as a way to launch things into the distance for hundreds of years. The earliest arrow-firing catapult, or device used to hurl objects for a distance, is believed to have been used in Greece in the year 399 BC—that’s a very long time ago!

Today, people still find ways to use catapults. The government uses steam-powered catapults to launch jet fighter planes into the air. In order to lift off the ground, an airplane has to get a lot of air moving over its wings. This isn’t a problem when an airplane takes off from a long airport runway. But how does a jet take off from the short deck of an aircraft carrier out in the middle of the ocean? The aircraft carrier has four catapults on board. These four catapults thrust the jet up to high speeds in a very short distance—and send it on its mission.
• 12

Try this next!

• Double the distance. Move the cup so it’s 24 inches (61 cm) from your kicking machine.
• Shoot it up and over. Build a ramp and see if you can shoot the ball up and over the ramp.
• Launch two balls at one time. Build a machine that can launch two balls at once or that can launch balls at different speeds.