# Ping Pong Ball Launcher: Teacher's Guide

## Introduction

### In this activity, the students will learn about force and motion through
playing with a ping pong ball launcher. They will test their knowledge by
trying to hit given targets.

## Goals

- Discover the relationship between launch angle and distance.
- Discover the relationship between spring extension (force) and distance.
- Develop graphing skills and be able to interpolate between data points.

## Background

### Around 1600, Galileo Galilei experimented with objects in motion. By
rolling balls down a ramp, he was able to conjecture that an object in
motion will not stop unless it interacts with something else.

### Galileo also showed that two objects of different masses will fall at the
same rate. It is commonly believed that he demonstrated this by dropping
objects off of the Leaning Tower of Piza.

### Galileo's experiments formed the basis for Isaac Newton's later
formulation of the laws of motion:

- An object in motion will remain in motion unless acted upon by an
outside force.
- The Force of an object is equal to its Mass times its Acceleration.
- For every action there is an opposite and equal reaction.

### These laws are still used today to determine everything from the distance a
baseball will fly to the motion of the space shuttle around the earth.

## Pre-Activity

### Get the students thinking about the trajectory of objects, such as
throwing a baseball, shooting a basketball, launching a satellite. What
"controls" do you have when throwing something? (angle and force)

## General Procedure

### Tasks for students

- Launcher
- Distance Marker
- Ball Retriever
- Angle Verifier (if needed)

- Pull plunger straight back and gently release for launch.
- Mark landing spot with chalk.
- Take all 3 shots, then measure and enter in table (measure from end
of launcher).

## Vary the Angle

- Launch at all the angles in table.
- Plot average distances.
- What angle will give farthest distance? The answer in an ideal world
is 45 degrees. Try testing 45 degrees. Is there a difference? If so, why?

## Vary the Extension

- Set the launcher to 45 degrees.
- Launch at the plunger extensions listed in the table. The extensions are
marked along the length of the dowel.
- Plot the average distances.
- What is the relationship? In an ideal world, using Newton's laws it
should be linear. Is there a difference? If so, why?

## Hit the Target

### Now for the fun- To use our new knowledge to hit a target.

- You have 10 balls.
- Give the students a distance and put the targets at that distance.
- From the 2 graphs, the students should decide at what angle and at
what extension to launch.
- Launch away!