Warm Up Simple Machines

Why are simple

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Simple machines are used to make work [moving an object a distance]

easier.

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Draw & Label the 3 types of levers

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Describe mechanical advantage

The ratio of output force to input force for a machine.

Ratio of resistance force to effort force in a machine.

The advantage created by a machine that enables people to do work while using less

force.

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– Why is the pulley considered a simple machine?

– What changes can be made to the pulley system to make work easier?

The pulley is considered a simple machine because it is designed to make work easier. Using a pulley would require less force to lift a

heavy object. Adding a longer rope to the pulley could help make work

easier.

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List the 6 types of simple machines

1. Lever

2. Pulley

3. Inclined plane

4. Screw

5. Wedge

6. Wheel & axle

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A construction worker tries to remove a nail from a board using a hammer and a crowbar.

The construction worker is not able to pull a nail out of a board using a hammer. When the worker tries using a crowbar, the

nail comes out easily.

–Use what you know about the relationship between work, force, and distance to explain why it was easier to use the

crowbar to remove the nail.

The crowbar is easier because it is longer than the hammer. Because it is longer, the crowbar

handle moves farther than the hammer. Because the crowbar pulls on the nail for a

greater distance, it can do as much work using a smaller force.

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The drawing below shows a student using a screwdriver to open a paint

can.

–To change the force to the lid of the paint can, the student can reposition her hand. How does

moving her hand change the force applied to the lid?

The student can move her hand closer or further from the end of the screwdriver to increase or

decrease the force applied to the lid.

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The drawing below shows a student using a screwdriver to

open a paint can.

–Describe how she could do this to apply less force to the

screwdriver to remove the lid.

To apply less force to the screwdriver to remove the lid, she

needs to move her hand to the end of the screwdriver's handle.

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The drawing below shows a student using a screwdriver to open a paint

can.

–Explain clearly how moving her hand allows her to change the force.

The mechanical advantage of a lever is dependent on the

distance the force is applied from the pivot. The larger the distance,

the smaller the force.