Simple Machines and Mechanical Advantage

Simple machines can do all of the following EXCEPT

• increase work done

• increase speed

• change direction of force

• increase force

Mechanical advantage is a measure of how much a machine multiplies the 

• efficiency.
• input force.
• output force.
• work.

It took 4000J of work to push the box up the inclined plane.  It would have taken 3500 J of work to lift the box up the same distance without the inclined plane.  What is the efficiency of the inclined plane?

• 114%
• 87.5%
• 95%
• Not enough data to determine

How can you decrease the input force needed to push a weight to the top of the ramp?

• cover the surface with carpet

• increase the length of the ramp

• increase the height of the ramp

• decrease the length of the ramp

Jeff is a landscaping contractor and lifts a rock weighing 600 N by wedging a board under the rock. Jeff weighs 150 N and puts all of his weight on the lever. How much actual mechanical advantage did the lever provide to Jeff in lifting the rock?

• 0

• 2

• 4

• 8

A lever is used to lift a fallen tree, which has a weight of 480 N. If the lever has a mechanical advantage of 5.5, what is the input force that will begin lifting the tree off the ground?

• 5.5 N
• 40.7 N
• 87.3 N
• 2640 N

Thermal energy is measured in

• watts

• joules

• newtons

• kelvin

The amount of work done depends on

• the size of the applied force

• the distance over which the force is applied

• the direction of the force

• the force size and distance

• size, distance and direction of the force

What is the ideal mechanical advantage of the block and tackle used to lift the bale of cotton?

• 1

• 2

• 3

• 4

This pulley

• has a mechanical advantage of 1 and does not make work easier.
• has mechanical advantage of 2 and reduces the force needed to lift an object.
• has a mechanical advantage of 2 and changes the direction of the applied force.
• has a mechanical advantage of 1 and changes the direction of the force needed to lift an object.