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:

1. An object in motion will remain in motion unless acted upon by an outside force.
2. The Force of an object is equal to its Mass times its Acceleration.
3. 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)

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

Vary the Angle

1. Launch at all the angles in table.
2. Plot average distances.
3. 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

1. Set the launcher to 45 degrees.
2. Launch at the plunger extensions listed in the table. The extensions are marked along the length of the dowel.
3. Plot the average distances.
4. 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.

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