Title: Parachutes and air resistance
1. Use 15 cm of string to tie two washers together securely.
2. One person from each group drop the washers from shoulder height (record distance) and observe their motion. Record the time it takes for the washers to hit the ground after being released.
3. Cut a 15x15cm square from the plastic bag and use the string and tape to create a parachute for the washers.
4. Have the same person who dropped the washers earlier hold the washers at shoulder height (same distance) while the other group members hold the parachute open above the washers.
5. Drop the washers and observe their motion. Record the time it takes for the washers to hit the ground after being released.
6. Compare your observations between the two trials and think about
what caused the differences.
- Air resistance is the force that opposes motion of objects through air
- Magnitude of air resistance depends on the size, shape and speed
- Terminal velocity is reached when upward air resistance equals the downward force of gravity.
- Something is in free fall only if gravity is the only force acting on an object. This can only occur where there is no air present.
1. How did the motion of the washers differ between the two trials?
2. What forces were acting on the washers and the parachute during the two trials?
3. Were the forces on the washers balanced or unbalanced? How do you know?
4. During which trial was the force of air resistance greater? Explain.
Skydivers count on air resistance against
their parachutes to slow them down before they reach the ground.
Videos: Include links to videos posted on the web that relate to your activity. These can be videos you have made or ones others have made.
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