Unit 5 Test: Work and Power

In which of the following is no work done?

• climbing stairs
• lifting a book
• pushing a shopping cart
• none of the above

A force acting on an object does no work if

• a machine is used to move the object.
• the force is not in the direction of the object's motion.
• the force is greater than the force of friction.
• the object accelerates.

What is the unit of work?

• joule
• newton/meter
• watt
• all of the above

If you exert a force of 10.0 N to lift a box a distance of 0.9 m, how much work do you do?

• 0.1 J
• 9.0 J
• 10.9 J
• 90.0 J

If you perform 40 joules of work lifting a 10-N box from the floor to a shelf, how high is the shelf?

• 0.3 m
• 20 m
• 4.0 m
• 400 m

The SI unit of power is the

• joule.
• newton.
• newton-meter.
• watt.

The power of a machine measures

• its time of doing work.
• its strength.
• the force it produces.
• the work it does.

If you exert a force of 700 N to walk 6 m up a flight of stairs in 6 s, how much power do you use?

• 19 W
• 25,200 W
• 700 W
• 4,200 W

A machine is a device that can multiply

• force.
• power.
• work.
• all of the above

How can a machine make work easier for you?

• by decreasing the amount of work you do
• by changing the direction of your force and multiplying it
• by increasing the work done by the machine
• none of the above