Bicycle Water Bombs: Hitting a Target from a Moving Object

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Updated on Dec 09, 2011

Grade Level: 6th to 8th; Type: Physics

Objective:

Using Newton’s first and second laws of motion, you will investigate the problem of hitting a target from a moving object.

Research Questions:

• Does changing the speed of your bicycle change the point at which you must release the cargo to hit your target?
• If so, how does it change the release point?

Newton's first law of motion states that a body in motion will maintain its motion unless acted upon by a force. Newton's second law of motion states that when a force acts upon a body in motion, the body accelerates in the direction of the force. Let's investigate these laws with a bicycle and water balloons.

Materials:

• Bicycle
• Level sidewalk or driveway
• Water
• Balloons
• Chalk
• Pen or pencil
• Lab notebook

Experimental Procedure

1. Fill three balloons with water and tie them off.
2. Use chalk to draw a target on the sidewalk.
3. Hold one water balloon as you ride down the sidewalk on your bike. Position the water balloon so that it's next to your handlebar.
4. While riding the bike, drop the water balloon the moment that it is directly over your target. Did it hit the target or land somewhere else? Where should you release the water balloon so that it lands directly on the target? Record your observations.
5. Repeat steps 3-6, but this time increase your speed. Record your observations.
6. Repeat steps 3-6, but this time decrease your speed. Record your observations.
7. Does changing the speed of your bike change the point at which you have to release the water balloon in order to get a direct hit? Applying the knowledge you've gathered from this experiment, what is involved in releasing cargo from a moving vehicle so that it will hit a direct target?

Terms/Concepts: Newton's first and second laws of motion, speed, release point

References: Science Projects About the Physics of Toys and Games, by Robert Gardner (Enslow Publishers, Inc., 2000).