#### Lesson 1

## The Lever

Even if Harry does not look tired and sweaty he has been performing work.

Work is force moved through a distance. The work we have set out to do is to lift (move)3500 N(force) 1 meter (Distance). In other words we can look at these three formulas which all describe moving our rock:

### **Work = Force X Distance**

*or*

### Work = Force of rock (FR) X Distance the rock moves (DR)

*or*

### 3,500Nm or 3,500 J (Joules) = 3,500N X 1m

*A Joule is the amount of work done when the force of 1 Newton moves a distance of 1 meter in the direction of the force. *

#### Data Analysis - 2: Comparing amount of work done between trials

Harry has not actually lifted the stone 1 meter but by using the lever, that work has been done. A force has been applied to the lever arm through a distance. Use the data from table 2 to calculate the work done by Harry on each of your successful tests to complete Table 3 in your lab packet.

- 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?
- 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?]

## In science and mathematics we describe the relationship between two variables (like effort and resistance) as either "direct" or "inverse."

### Direct

In a direct relationship, if one variable increases in value, the other variable also increases. (Make more money, pay more taxes)

### Inverse

In an inverse relationship, if one variable increases the other variable decreases. (Spend more money, savings goes down.)

#### Data Analysis - 3: Calculating Mechanical Advantage (MA)

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. The rock(FR) has a force of its weight (3500Nm) and the distance the rock moves (DR) is only 1 meter.

Harry had to move a longer distance than the stone BUT he 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?
- Comparing different trials: as the effort distance increases, what happens to the effort force (FE)?

Talk Now - 1e

With your lab partner, create a statement explaining the mechanical advantage of using a lever to lift a heavy mass.

Complete the rest of your lab packet and then let's move on to Lesson 2 - The Ramp and Pulley.