Key words: Simple machines, Class 1, Class 3, lever, distance mechanical advantage, fulcrum, force, effort, load, weight, physical science, Ron Kurtus, School for Champions. Copyright © Restrictions

# Increasing Distance Moved with a Lever

by Ron Kurtus (20 November 2014)

You can use a Class 1 or Class 3 lever to increase the distance that the load moves, according to where the fulcrum is located. To increase the distance moved, the length of the load arm of the lever must be greater than the length of the effort arm.

The equation for the distance moved relates to the distance mechanical advantage of the lever. From the equation, you can determine an unknown distance or length.

Questions you may have include:

• What do the Class 1 and Class 3 levers look like?
• What is the distance equation?
• What is an example of an application?

This lesson will answer those questions. Useful tool: Units Conversion

## Using Class 1 or Class 3 lever

You can increase the distance a load moves as compared to the distance the effort moves with either a Class 1 or a Class 3 lever.

Increase the distance the load moves with a Class 1 lever

You could use such a lever to lift a box to some that might be too high to reach. However, what you gain in distance or height requires a greater effort force. Thus in many cases, the Class 1 lever is used, because pushing down with your weight is easier than pulling up.

Increase the distance the load moves with a Class 3 lever

Since the load length (dL) is longer for a given lever length, the Class 3 lever would have a greater distance mechanical advantage and be able to lift the object higher.

## Distance equation

The relationship between the effort distance and load distance is dependent on the ratio of the arms of the lever, according to the equation:

DL/DE = dL/dE

where

• DL is the distance the load force is moved
• DE is the distance the effort forces moves
• dL is the length of the load arm
• dE is the length of the effort arm

Note that dE and dL are inverted compared with the force equation.

Also note that DL/DE is the distance mechanical advantage of the lever.

## Application

Suppose you wanted to lift a box to a height of 1 meter. You have a lever that is 2 meters long. You place the fulcrum at 0.5 meters from where you will apply your effort. How far do you push down? In other words, solve for DE.

DL/DE = dL/dE

Using Algebra, rearrange the equation to get:

DE = DLdE/dL

Substitute values:

DL = 1 meter

dL + dE = 2 m

dE = 0.5 m

dL = 2 − 0.5 = 1.5 m

Thus, the distance the effort must move is:

DE = 1*(0.5)/1.5 = 0.33 m

The mechanical advantage of this lever is:

MAD = DL/DE = 1/0.33 = 3

## Summary

You can use a Class 1 or Class 3 lever to increase the distance that the load moves, according to where the fulcrum is located. To increase the distance moved, the length of the load arm of the lever must be greater than the length of the effort arm.

The equation for the distance moved relates to the distance mechanical advantage of the lever. From the equation, you can determine an unknown distance or length.

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## Resources and references

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