Leverage

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Introduction:
Levers allow us to lift objects that are much heavier than we are. How is that possible?

Activity:
Visit three Lever Stations as directed by your teacher. Read the card, try the activity, and discuss the questions with your partners.
 * In this station, pretend that a father and his young son want to play on the see-saw. Arrange the "father" weight and the "son" weight so they balance.
 * How did you have to arrange the two weights?
 * The father" weight is twice as heavy as the "son" weight. Is the "son" twice as far from the fulcrum?
 * Who moved more in this see-saw--"father" or "son"?
 * In this station, please arrange the lever arm and fulcrum so that the alien toy can lift the brick.
 * How did you have to arrange everything?
 * Which was heavier--the alien or the brick?
 * Which moved farther--the alien or the brick?
 * Try lifting the wooden plank just off the table, using one rubber band at a time.
 * Which rubber band stretched more?
 * Which was harder to pull?
 * Which required more force?
 * Now try lifting the wooden plank to a vertical position by gripping one eye-screw at a time.
 * Which one was harder to pull (at first)?
 * Which one made your fingers move farther?

Conclusion:
What do scientists mean by "FORCE-DISTANCE TRADEOFF"?

Enrichment:
[|Raising the Moai on Easter Island (Edited to <5 min.)] Entire Episode: media type="youtube" key="xc8Xio0xWUc" height="344" width="425"