Work, Power, and Machines

If you have to apply 40 N of force on a crowbar to lift a rock that weighs 400 N, what is the actual mechanical advantage of the crowbar?

• 0.1

• 10

• 360

• 16,000

How can you make the work output of a machine greater than the work input?

• by decreasing friction

• by increasing the input force

• by increasing the output distance

• none of the above

A machine is a device that can multiply

• force.

• power.

• work.

• all of the above.

A 750-W motor might also be rated as a

• 0.5-horsepower motor.

• 1-horsepower motor.

• 2-horsepower motor.

• 10-horsepower motor.

If you know the input distance and output distance of a machine, which of the following can you calculate?

• work

• actual mechanical advantage

• efficiency

• ideal mechanical advantage

When a machine does work, if cannot do which of the following?

• change the direction of a force.

• increase a force and change the distance a force moves.

• increase the distance a force moves and change the direction of a force.

• increase a force and increase the distance a force moves an object.

The actual mechanical advantage of a machine

• cannot be less than 1.

• decrease as the input distance increases.

• increases with greater friction.

• is less than the ideal mechanical advantage of the machine.

3730 watts equal about how many horsepower?

• 5

• 10

• 20

• 30

How can a machine make work easier for you?

• be decreasing the amount of work you do.

• by changing the direction of your force.

• by increasing the work done by the machine.

• none of the above.

An example of a compound machine is a

• crowbar.

• bicycle.

• ramp.

• seesaw.