# Physical Science Chapter 7 Study Guide

## 24 terms

### Resistance force

The force needed to just begin moving the resistance is the...

The system to be moved by a simple machine is called the...

### Wheelbarrow

An example of a second class lever is a

### See-saw

An example of a first class lever would be a...

### gear

A wheel with notches or teeth round its circumference is a...

### wedge

A _______ is two inclines planes back to back.

### block and tackle

An example of multiple pulleys called "gangs" is a...

### inclined planes

The Egyptians used ______ to help build their pyramids.

### lever

A ______ is simply a rigid bar that rests on a pivot point called a fulcrum.

### wheel and axle

One advantage of using a ________ is that it allows a continuous force to be applied.

### fulcrum

In a first class lever the _______ is located between the effort and the resistance.

### screw

An inclined plane that is wrapped around a shaft, generally used as a fastener is a...

### none of the above

________ is an example of a third class lever.

wheelbarrow
see-saw
pry bar
none of the above

### pulley

A wheel with a groove around its outer circumference mounted on an axle is a...

### effort arm

In a second class lever the fulcrum is at the end of the...

### True

True or False? Mechanical work occurs when a force acts on an object to move it in a direction parallel to the force vector.

### False

True or False? A see-saw would be classified as a 2nd class lever.

### third class levers

Most human bones in the human body form __________________________.

### work and energy

What does the joule measure?

### Power equals work divided by the time interval

What is the formula for power?

### True

True or False? You cannot get more work out of a machine than you put into it.

### watt

What is the unit of power?

### False

True or False? Simple machines reduce the amount of work needed to complete a project.

### 3

There are ___ different classifications of levers?