Physics Work and Machines

In SI, the units for work and energy is

Joules

The SI unit for power is

Watts

To calculate work, multiply force by

Displacement

Power is the ____ at which work is done

rate

A kilowatt is equal to

1000 watts

If a force acts ______ to the direction of the displacement, no work is done

perpendicular

Your car is stuck in the mud and you ouch with a force of 230 N for 160 seconds. out of have done___ work

Zero

You carry a crate of books up one flight of stairs in 10 seconds, you then carry the identical crate up the same flight of stairs in 45 seconds. Both jobs require the same total amount of ____ but different amounts of ____

work; power

A crate slid down a ramp is negative work.

Negative work

A backpack is lifted is

positive work

A toy is wound up is

positive work

A sledge hammer hit against a wall is

negative work

Work equals change in

energy

In an ____ machine the work in equals work out

ideal

Is the most common cause for losses in a machine

Friction

Machines make work easier by changing either the ___ or ___ of an applied force

direction; magnitude

You push down on a lever to lift the weight of a heavy rock. The _____ is the effort force and the ____ is the resistance force

push; weight

What are the six types of simple machines?

Lever, pulley, inclined plane, wheel and axe, wedge, and screw

A combination of 2 or more machines is a UU machine

Compound