# Work and Machines

## 30 terms

### force and distance

The amount of work done on an object is obtained by multiplying

### changing the direction of your force.

One way a machine can make work easier for you is by (flag pole)

### nutcracker, scissors, knife

The output force is greater than the input force for a

### seasaw, wheelbarril, bottle opener

What is an example of a second-class lever?

### bicycle, pencil sharpener, door knob

Give an example of a complex machine?

### no work is done.

If none of the force on an object is in the direction of the object's motion,

### friction

What reduces the efficiency of a machine?

### efficiency

What is the comparison between output work and input work?

### screw

What type of machine is an inclined plane wrapped around a central cylinder?

### wedge

What type of machine are your front teeth?

### joule

What is the unit of work?

### 100%

What is the efficiency of an ideal machine?

### Efficiency = Output work divided by input work

What is the formula for efficiency?

### changing the direction.

A machine can make work easier by

### wedge

An ax, a zipper, and a front tooth are examples of what type of simple machine?

### ideal mechanical advantage of wheel and axle

What are you finding when you divide the radius of a wheel by the radius of an axle?

### gears

What is a compound machine with one wheel and axle linked to another wheel and axle?

### fulcrum

The fixed point that a lever rotates around

### combinatons of simple machines

Compound machines are

### elbow.

When you bend your arm at the elbow, the fulcrum is at your

### move some distance

In order to do work you must

the number of times a force exerted on a machine is multiplied by the machine.

### axle

In a screwdriver, the handle is the wheel and the shaft is the

### tendons

Muscles are attached to bones by

The more efficient the machine is, the closer the actual mechanical advantage is to the

### does not decrease

a machine ______ the amount of work you do.

### screw

An inclined plane wrapped around a cyliner is a

### pulley

What simple machine is a rope wrapped around a grooved wheel?

### direction

A singe fixed pulley, such as a flagpole, changes the

### wedges

When you bite into a sandwich, your front teeth act as