# Ping Pong Catapult Instructions

Hi, this is Lily Arendt with Science Buddies
and this video is an introduction to our ping pong catapult kit. When you open the box, you should find the
catapult, three rubber bands, a clamp, a ping pong ball, and a whiffle ball. First, pull out the locking pin. This separates the catapult arm from the catapult
base and allows it to rotate. Next, attach the black catapult base to the
edge of a sturdy table or desk using the clamp. The base is metal, so you might want to use
a towel as padding to avoid scratching your furniture. Next, take the locking pin, insert it through
the hole in the base, and one of the holes in the circular disc. This sets the launch angle, or the angle at
which the ball will travel relative to the ground when it’s launched. Here you can see that the launch angle is
set to forty five degrees. Now, take a rubber band, thread it through
the large hole at the top of the disc, and hook it on to the two pegs sticking out the
sides of the catapult arm. Pulling the arm back allows you to set the
pull-back angle, or the angle it will travel through before it hits the rubber stopper. For example, here the pull-back angle is sixty
degrees. To use the catapult, place the ball in the
suction cup, pull the arm back, and release. When you pull the catapult arm back, potential
energy is stored in the stretched rubber bands. This is converted to kinetic energy of the
ball when it is launched. The catapult allows you to easily change four
different independent variables. You can change the pull-back angle, the launch
angle, the number of rubber bands, or the type of ball. For a fun classroom experiment or science
project, try changing one of these independent variables, and measure how far the ball travels
using a tape measure. To see written instructions for these projects
or to purchase a catapult kit, visit us online at www.sciencebuddies.org.