Why are simple machines used Seconds Remaining 140

Why are simple machines used? Seconds Remaining: 140 120 130 30 40 50 60 70 10 2 3 4 5 6 7 8 9 180 20 160 90 150 170 100 110 1080

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

Draw & Label the 3 types of levers Seconds Remaining: 140 120 130 30 40 50 60 70 10 2 3 4 5 6 7 8 9 180 20 160 90 150 170 100 110 1080

Describe mechanical advantage Seconds Left: 140 120 130 30 40 50 60 70 10 2 3 4 5 6 7 8 9 0 180 20 160 90 150 170 80 100 110 1

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.

– Why is the pulley considered a simple machine? – What changes can be made to the pulley system to make work easier? Seconds Left: 120 140 130 70 60 50 40 30 10 9 8 7 6 5 4 3 2 0 180 80 20 160 90 170 150 110 100 1

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.

List the 6 types of simple machines 140 120 130 30 40 50 60 70 10 2 3 4 5 6 7 8 9 0 180 20 160 90 150 170 80 100 110 1 Seconds Left

1. 2. 3. 4. 5. 6. Lever Pulley Inclined plane Screw Wedge Wheel & axle

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. Seconds Left: 120 140 130 70 60 50 40 30 10 9 8 7 6 5 4 3 2 0 180 20 160 90 80 170 150 110 100 180

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.

The drawing below shows a student using a screwdriver to open a paint can. Seconds Left: 140 120 130 30 40 50 60 70 10 2 3 4 5 6 7 8 9 0 80 180 20 160 90 150 170 100 110 1 –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.

The drawing below shows a student using a screwdriver to open a paint can. Seconds Left: 140 120 130 30 40 50 60 70 10 2 3 4 5 6 7 8 9 0 180 20 160 90 170 150 80 100 110 1 –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.

Seconds Left: The drawing below shows a student using a screwdriver to open a paint can. 140 120 130 30 40 50 60 70 10 2 3 4 5 6 7 8 9 0 180 20 160 90 150 170 100 110 80 1 –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.