Science Test; Machines

To which class of lever does each of the following machines belong: (i) fishing pole; (ii) wheelbarrow; (iii) bottle opener; (iv) pliers?

(i) is 3rd (ii) is 2nd (iii) is 2nd (iv) is 1st

An ideal machine would have an efficiency of

100%

The efficiency of an actual machine is always less than

100%

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

1

Which machine has the greatest ideal mechanical advantage?

5

The output work of a certain machine is 12,600 J. If the input work is 18,000 J, the efficiency is

70%

One example of a compound machine is a

Bicycle

A machine that utilizes two or more simple machine sis called a

Compound machine

Which of these is an example of a third-class lever

Fishing pole

True or false. The ideal mechanical advantage of a wheel and axle is the radius of the wheel TIMES the radius of the axle.

False; Divided by

True or false. JOULE is the rate at which work is done.

False; Power

True or false. A wheel and axle is a COMPOUND machine

False; Simple

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

Friction

In machine 2, which letter represents the input force

G

In order to do work on an object, the force you exert must be

In the same direction as the object's motion

A ramp in a parking garage is an example of a simple machined called a(n)

Inclined Plane

The force applied to a machine is called the _____ force.

Input

How can a hockey stick be considered a machine?

It multiplies distance

Which body parts act as the fulcrums of levers?

Joints

A paint can opener acts as a simple machine called a

Lever

The wedge, screw, and lever are all

Simple Machones

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

Radius of the wheel divided by the radius of the axle

A gardener pushes on the angled handle of a lawn mower, causing the mower to move forward across a lawn. The only portion of the gardener's force that does work on the lawn mower is the force in the _______ direction.

Same

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

Screw

Which of these could be considered an inclined plane wrapped around a cylinder?

Screw

True or false. The force exerted by a machine is called the OUTPUT force

True

True or false. You do WORK on an object when you lift it off the floor onto a shelf.

True

A device that is twice as powerful as another can do ________ the amount of work in the same amount of time.

Twice

Power is measured in units called

Watts

A simple machine that might be thought of as an inclined plane that moves is a

Wedge

A screwdriver is a simple machine called a

Wheel and axle

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

height of the incline

Most of the machines in your body consist of bones and muscles acting together as

levers

For work to be done on an object,

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