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Chapter 12

100

For work to be done on an object

a. the object must move, whether or not a force is exerted on it.

b. some force need only be exerted on the object.

c. the object must move some distance as a result of a force

d. the object must move a distance equal to the amount of force exerted on it.

c. the object must move some distance as a result of a force.

200

Pulling down on a rope to hoist a sail on a sailboat is an example of a machine

a. multiplying force

b. multiplying distance.

c. reducing friction

d. changing direction.

d. changing direction

300

Without friction there would be

a. greater input work than output work

b. greater output work than input work

c. equal input and output work

d. less machine efficiency

c. equal input and output work

400

What do machines do

a. eliminate friction

b. increase work

c. change force over distance

d. decrease work

c. change force over distance

Types of Machines

100

a machine that uses two or more simple machines is called a 

a. compound machine

b. mechanical machine

c. mixed machine

d. combination machine

a. compound machine

300

A jar lid is an example of a simple machine called?

screw

Mechanical Advantage

100

The mechanical advantage of a machine that changes the direction of force only is

a. less than 1.

b. 1.

c. zero.

d. greater than 1.

b. 1

200

The efficiency of a machine compares

a. output work to input work

b. friction to mass.

c. force to mass.

d. force to friction.

a. output work to input work

300

The ideal mechanical advantage for an inclined plane is equal to the length of the incline divided by the

a. height of the incline

b. slope of the incline

c. angle of the incline

d. mass of the incline

a. height of the incline

400

The ideal mechanical advantage of a wheel and axle is equal to the 

a. radius of the wheel divided by the radius of the axle

b. radius of the wheel divided by the length of the axle

c. radius of the axle divided by the radius of the wheel

d. length of the axle divided by the radius of the wheel

a. radius of the wheel divided by the length of the axle

500

The ideal mechanical advantage would equal the actual mechanical advantage if there were no losses due to?

friction

Misc.

100

Most machines in your body, which consists of bones and muscles, are

a. pulleys

b. compound machines

c. wedges

d. levers

D. levers

200

Which body parts are shaped like wedges?

a. bones and legs

b. incisors 

c. tendons

d. muscles

b. incisors

300

The efficiency of a machine compares

a. output work to input work

b. friction to mass

c. force to friction

d. force to mass

a. output work to input work

Work and Levers

100

Work = force x

a. distance

b. energy

c. mass

d. velocity

a. distance

200

Work is measured in 

a. meters

b. newtons

c. joules

d. pounds

c. joules

300

Why would it be impossible to build this fourth class of lever depicted on the board?

the machine multiplies both force and distance. the output work of this machine would be greater than the input work, which is impossible because a machine cannot do more output work than input work.

400

Which class of lever does not multiply the input force?

Class 3. A third-class lever multiplies the distance of the input force

500

What class of lever is a pair of scissors?

Class 1