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What do you notice about the amount of work done in each successful trial?
- Compare the effort distance (DE) and effort force (FE) in all trials. What happens to the amount of (FE) as the (DE) increases?
- Did you notice that when one amount changes the other amount will change in a specific way?
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In science and mathematics we describe the relationship between two variables (like effort and resistance) as either "direct" or "inverse"
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In a direct relationship, if one variable increases in value, the other variable also increases. (Make more money, pay more taxes)
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In an inverse relationship, if one variable increases the other variable decreases. (Spend more money, savings goes down)
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- Use the term "inverse" or "direct" to explain the relationship between effort force and effort distance as you adjusted your lever. (Use complete sentences)
- What are the advantages of using a lever to lift this stone? Hints: [Could you lift the stone without the lever or any other piece of equipment? In what direction did Harry apply the force?]
We can give these advantages a mathematical value. It is called Mechanical Advantage (MA).
The lever we have been using works when we apply the effort force (FE) through a longer distance than the stone (FR) moves.
We had to move a longer distance than the stone BUT we didn't have to apply as much force.
- Use the same data again to complete Table 4 in your packet.
- When you have completed Table 4, Calculate the MA both ways for each successful test.
- Can you draw any conclusions about the MA calculated using the forces and the MA calculated using the distances for each trial?
Comparing different trials:
- As the effort distance increases, what happens to the MA?
- As the effort distance increases, what happens to the effort force (FE)?
- With your lab partner, create a statement explaining the mechanical advantage of using a lever to lift a heavy mass.
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