Chapter 3 work and simple machines

Which is the SI unit of work?

• ampre

• joule

• newton

• watt

Which transfers both kinetic energy and potential energy to an object?

• lifting it

• lowering it

• pushing it

• rolling it

Which is third-class lever

• a broom

• a hammer

• a nutcracker

• a wheelbarrow

Mechanical advantage = output force/? what correctly completes the mechanical advantage equation?

• distance

• time

• input force

• output force

A simple machine is NOT able to

• change the size of a force

• decrease the amount of work required

• exert an output force on an object

• make work easier to perform

Which MUST happen in order for work to be done?

• A force must move an object

• A machine must transfer force

• Force must be applied to an object

• Output force must exceed input force

Which increases the efficiency of a complex machine?

• adding more simple manchines

• increasing input force

• putting more work in

• reducing friction by lubricating

What information is needed to calculate the ideal mechanical advantage of an inclined plane?

• its height and length

• its length and thickness

• its thickness and weight

• its weight and width

Which is a characteristic feature of a wedge?

• cable

• fulcrum

• slope

• thread

Which must be true when work is done?

• No force acts on the object

• An object slows down

• An object moves quickly

• An object moves in the same direction as a force exerted on it