Work, Power, and Machines

What is work?

• Work is using a force to make an object change.

• Work is when an object moves in the same direction as the applied force.

• Work is washing dishes and doing laundry.

Which is an example of scientific work?

• Doing a math worksheet

• Babysitting a neighbor's child

• mowing the lawn

What is FORCE?

• Force is energy

• Force is what is with Luke Skywalker

• Force is a push or a pull

Which are the correct measurement units for Work, Power, and Force?

• Work = Newtons (N) Power = Watts (W) Force = Joules (J)

• Work = Watts (W) Power = Newtons (N) Force = Joules (J)

• Work = Joules (J) Power = Watts (W) Force = Newtons (N)

Simple Machines: A pulley makes work easier by changing the direction of the force so you are pulling with gravity instead of lifting against it.

• true

• false

A lever makes work easier by changing the direction of the force so that you can push down with gravity instead of lifting up against gravity.

• True

• False

Simple Machines:

An inclined plane makes work easier by changing the direction of the force.

• true

• false

Simple Machines:

An inclined plane makes work easier by spreading the force out over a greater distance, so less force has to be applied.

• True

• False

Can a machine be 100% efficient?

• Yes, if it's designed well.

• No, because of energy transformation by friction.

Is the penguin doing work as he carries the briefcase?

• Yes -- and he's cute too!

• No, because he's applying an upward force to the briefcase, but his motion is forward. Work requires the force and motion to be in the same direction.