Work, power & machines

Work is the product of

• speed and force

• force and distance

• power and force

• motion and force

Is the rate of doing work.

(a)  

Wich of the following is a unit of work?

• Joule

• Watt

• Horsepower

• Newton

How much work in N*m (J), is done when a 10.0 N force moves an object 2.5 m?

• 0.25 N*m

• 2.5 N*n

• 25 N*m

• 4.0 N*m

Power is equal to work divided by

• time

• force

• distance

• mechanical advantage

If a machine has a mecanichal advantage much larger than 1, its output force is

• much larger than its input force.

• much less than its input force.

• about the same as its input force.

• in the same direction as its input force

How is the work output of a machine related to its work input?

• always less

• always greater

• always equal

• always zero

A machine with a 5 N input force and a 25 N output force has a mechanical advantage of

• 2

• 5

• 20

• 125

Write 2 of the simple machines

(a)  

The mecanical advantage of a pulley system depends upon

• the diameter of the pulley wheels

• the lenght of the rope

• the number of sections of rope

• the direction of the input force