# Newton’s Laws, Friction, and Hovercraft

## A Carolina Essentials™ Activity

##### Total Time: 30 mins

Prep: 30 mins | Activity: 30 mins

## Overview

Students can engineer a simple hovercraft that illustrates Newton’s laws of motion and frictional force. Newton’s laws explain how the craft “hovers” above a surface and how the craft reacts to an applied force. Introduce frictional force when the hovercraft is inflated, as it glides over the floor on a cushion of air, and after it rests on the floor.

## Activity Objectives

1. Build a working model hovercraft using inexpensive household items.
2. Observe the effect of friction on a mechanical system.

## Next Generation Science Standards* (NGSS)

PE HS-PS2-1. Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration.

### Science & Engineering Practices

Planning and Carrying Out Investigations

### Disciplinary Core Ideas

PS2.A: Forces and Motion

### Crosscutting Concepts

Stability and Change

## Safety Procedures and Precautions

Glue guns are a source of heat. Hot glue can stick to fingers and burn the skin. Follow all directions carefully.

### Student Procedures

1. Position the soap bottle cap over the center hole of the CD. Draw a circle around the cap.
2. Using the drawn circle as a guide, attach the soap bottle cap to the CD with hot glue.
3. Make sure the hot glue provides an airtight seal around the edge of the cap.
4. Allow the glue to dry.
5. Make sure the soap bottle cap is closed and pushed downward.
6. Inflate the balloon.
7. Twist the neck of the balloon to stop the air from escaping.
8. Stretch the neck of the balloon over the plastic tip of the cap. Make sure the balloon is securely attached to the cap so that no air can escape.
9. Place the balloon on a flat surface, such as a lab table or a tile floor.
10. Pull up on the cap so that air escapes from the balloon through the cap and the hole in the CD.
11. Gently push the hovercraft and observe how it moves across the floor.
12. When the balloon is completely deflated, push the hovercraft again.
13. Sketch the motions of the hovercraft.

### Teacher Preparation and Tips

1. The soap bottle cap must be one that pulls up to open.
2. Prepare hot glue guns early so students do not have to wait for them to heat up. Reinforce that the glue is hot and will stick to their skin.
3. You may want to purchase balloon pumps so students do not have to put their mouths on the balloons.
4. You may want to purchase balloon pumps so students do not have to put their mouths on the balloons.
5. Physics students should sketch free body diagrams for the hovercraft.
6. For a more complete study on friction, have students observe the hovercraft on several surfaces, such as carpet, a wood floor, a waxed tile floor, water, grass, or asphalt.

## Data and Observations

Students should sketch and describe the motions of the hovercraft.

Descriptions and sketches will vary.

## Analysis & Discussion

1. Explain in detail which of Newton’s laws were illustrated in this activity.

Students must include inertia, F = ma, and action/reaction. Some may use the second law to explain how the force they exert on the CD can change the velocity at which the hovercraft travels. They should also note that friction is the force that slows or stops the motion of the hovercraft.

2. Explain differences in the force of friction between the hovercraft on a smooth surface and on a rough surface.

There is more friction when the CD is pushed along the floor than when the CD is moving through the air.

3. Use a diagram illustrating the microscopic view of the surfaces to generate a model for friction in this activity.

A hovercraft generates a cushion of air that prevents the solid surface of the hovercraft from making contact with the ground surface, thereby reducing friction.

### Don’t Quote Me on That: Math Attitude Card Sort

*Next Generation Science Standards® is a registered trademark of Achieve. Neither Achieve nor the lead states and partners that developed the Next Generation Science Standards were involved in the production of, and do not endorse, these products.