Work

What are two things that have to happen for work to be done?

Has to move in the same direction as the force.

Why can't you get more work out of a machine than you put into it?

Machines don't increase trhe amount of work that is done. They just change how the work is done.

Explain how a machine makes work easier.

Machines make work easier by increasing the amount of force that is applied, increasing the distance over which the force is applied, or changing the direction in which the force is applied.

Explain why machines are not 100% efficient.

That's because all machines must use some of the work put into them to overcome friction

Explain the difference between work & power

Work is how much force it takes to move an object in the same direction. Power is how long it takes you to do the work.

Machine

any device that makes work easier by changing a force.

Mechanical advantage

is the number of times a machine multiplies the input force.

Mechanical efficiency

is the percent of input work that becomes output work. It is a measure of how well a machine reduces friction.

Identify three different ways that machines may change force.

• Increase the force • Increase the distance of the force • Change the direction of the force