Chapter 12

Question 1

Work

Answer 1

The transfer of energy to an object by the application of a force that makes the object move in the direction of the force.

Question 2

Power

Answer 2

A quantity that measures the speed at which work is done.

Question 3

Mechanical Advantage

Answer 3

A quantity that measures the amount a machine multiples force force or distance.

Question 4

Joule

Answer 4

The unit used to calculate work. Joule is equivalent you 1 kgXm^2/s^2.

Question 5

Watt

Answer 5

The unit used to measure power.

Question 6

Simple machines

Answer 6

One of the six basic types of machines, which are the basis for all other forms of machines.

Question 7

Compound machine

Answer 7

A machine which is made of more than one simple machine.

Question 8

Lever

Answer 8

An example of a lever is a hammer pulling out a nail. The force applied to the hammer is transferred to the claw on the other end of the hammer.

Question 9

First class lever

Answer 9

All first class levers have a fulcrum located between the points of application of the input and output forces

Question 10

Second class lever

Answer 10

The fulcrum is at one end of the arm and the input force is applied to the other end. The wheel of a wheelbarrow is a fulcrum.

Question 11

Third class levers

Answer 11

Third class levers multiply distance rather than force. As a result, they have a mechanical advantage of less than 1.

Question 12

Pulley

Answer 12

A pulley is another type of simple machine in the lever family.

Question 13

Block and tackle

Answer 13

Multiple pulleys that are sometimes put together in a single unit

Question 14

Wheel and axle

Answer 14

A wheel and axle is made of a lever or a pulley connected to the shaft.

Question 15

Inclined plane

Answer 15

An inclined plane turns a small input force into a large output force by spreading the work out over a large distance.

Question 16

Wedge

Answer 16

A wedge turns a downward force into two forces directed out to the sides.A wedge acts like two inclined planes back to back.

Question 17

Screw

Answer 17

A screw is an inclined plane wrapped around a cylinder.

Question 18

Potential energy

Answer 18

The energy of an object has because of the position, shape, or condition of the object.

Question 19

Kinetic energy

Answer 19

The energy of a moving object because of the object’s motion.

Question 20

Mechanical energy

Answer 20

The amount of work an object can do because of the object’s kinetic and potential energies.

Question 21

Elastic potential energy

Answer 21

The energy stored in any type is stretched or compressed elastic material, such as a spring or bungee cord.

Question 22

Gravitational potential energy

Answer 22

Any system of two or more object’s separated by a distance contains gravitational potential energy resulting from the gravitational attraction between the objects.

Question 23

Non mechanical energy

Answer 23

Energy that lies at the level of atoms and that doesn’t affect motion on a large scale

Question 24

Efficiency

Answer 24

A quantity that is mostly expressed as a percentage, and measures the ratio of useful work output to work input.

Question 25

Open system

Answer 25

Systems that exchange energy with the space that surrounds them

Question 26

Perpetual motion machines

Answer 26

A machine that is designed to go on forever without any input of energy.

Question 27

Closed systems

Answer 27

When the flow of energy into and out of a system is small enough that it can be ignored