Chapter 12 Work And Energy

Question 1

Work

Answer 1

The transfer of energy to a body by force that causes the body to move in the direction of the force.

Question 2

Power

Answer 2

A quantity that measures the rate at which work is done or energy is transformed.

Question 3

Mechanical Advatage

Answer 3

A quantity that measures how much a machine multiplies force or distance.

Question 4

Joule

Answer 4

Newton’s•meters. Unit for work.

Question 5

Watt

Answer 5

Unit of measure for power. A watt is the amount of power required to do 1 joule of work for 1 second.

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 Machines

Answer 7

A machine made of more than one simple machine.

Question 8

Lever

Answer 8

Has a rigid arm that turns a point called the fulcrum.

Question 9

First Class Lever

Answer 9

Has a fulcrum located between two points of application of 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 on the other end.

Question 11

Third Class Lever

Answer 11

Multiply distance rather than force. Mechanical advantage of less than 1.

Question 12

Pulley

Answer 12

Works like a Lever. The middle point of the pulley is like the fulcrum. The rest behaves like the arm of a lever.

Question 13

Block and Tackle

Answer 13

Multiple pulleys put together in a single unit.

Question 14

Wheel and Axle

Answer 14

Like a lever or pulley connected to a shaft. When the wheel is turned, the axle also turns.

Question 15

Inclined Plane

Answer 15

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 modified inclined plane. Using a wedge is like pushing a ramp rather than pushing an object up a ramp.

Question 17

Screw

Answer 17

An inclined plane wrapped around a cylinder.

Question 18

Potential Energy

Answer 18

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

Question 19

Kinetic Energy

Answer 19

The energy of a moving object due to 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 of stretched or compressed elastic material, such as a spring or bungee cord.

Question 22

Gravitational Potential Energy

Answer 22

Depends both on the mass of the object’s in a system and on the distance between them.

Question 23

Nonmechanical Energy

Answer 23

Energy that lies at the level of atoms and that does not affect motion on a large scale.

Question 24

Efficiency

Answer 24

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

Question 25

Open System

Answer 25

Exchange energy with the space around them.

Question 26

Closed System

Answer 26

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

Question 27

Perpetual Motion Machine

Answer 27

A machine designed to keep on going forever without any input of energy.