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## High school physics

### Course: High school physics>Unit 5

Lesson 8: Explore simple machines

# Lever

PLEASE NOTE: Some of the videos in this section are silent to allow the viewer to make their own observations about what is happening and respond to the questions posted below.
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This video has no sound.
1. What happens to the amount of force needed to move the right side when the fulcrum is shifted to the right?
2. What happens to the distance that left side travels when the fulcrum is shifted to the right?
3. When the fulcrum is shifted to the right, which side has a mechanical advantage and which side has a mechanical disadvantage?
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If you are doing high school level math then you may want to check out these mechanical advantage lever videos:
Khan Academy video wrapper
Introduction to mechanical advantageSee video transcript
Khan Academy video wrapper
Mechanical advantage (part 2)See video transcript

## Want to join the conversation?

• How is simple machine useful in lifting thing
• Simple machines increase force, increase distance, and change direction
• Is there a relationship between the distance the load force moves and the distance the effort force moves?
• Absolutely! He explains this in the mechanical advantage videos but more easily you can think of it like a wrench turning a stuck bolt. Just using the wrench doesn't work but if you put a pipe on the handle of the wrench to extend the handle, the bolt easily breaks loose. Why? Because the force you apply times the distance of the handle creates what we call a "moment" (a turning force) on the bolt. Mathematically expressed" F * d = P (where P is the moment)
• What materials do you use for this demonstration so that we can try a hands-on as well? Thanks!
• Hi! You could use a ruler and a slim pencil rubber. The advantage of using a ruler is that you can literally measure the distances as you change the mechanism! And the rubber won't let the ruler slide apart, but remeber that it has to be slim, otherwise it won't represent a fulcrum. As for the weight, some coins will do the job. Hope you can do it yourself! Thank you!
• How does the machine not have one side go down at first? At somewhere around the lever should be tilted the other way because there is no force being applied on the opposite side.
• when the weights were added in the 3rd type of lever, why did the left side go downwards even though there was a large number of coins on the other side?
• in the middle of the video how did he know to put on the coins