Chapter 12 Work And Energy

Question 1

Work

Answer 1

Transfer of energy to an body by a force and causes it to move in the direction of the force

Question 2

Power

Answer 2

Rate in which work is done or energy is transformed

Question 3

Mechanical advantage

Answer 3

Measures the how much a machine multiples force of distance

Question 4

Joule

Answer 4

The unit for work

Measured as Newton’s times meters

Question 5

Watt

Answer 5

Unit for power

Amount of power required for 1 J of work in 1 s

Question 6

Simple machines

Answer 6

One of 6 types of machines

Basis of all other forms of machines

Question 7

Compound machines

Answer 7

Machine made of more than one simple machine

Question 8

Lever

Answer 8

Have a rigid arm that turns around a point where force is transferred from one part of the arm to the other

Question 9

First class lever

Answer 9

.most common type

Example is claw hammer

Question 10

Second class lever

Answer 10

.examples include nutcrackers, hinged doors, wheelbarrows

Question 11

Third class lever

Answer 11

Examples are human forearm

Biceps are attached to bone near the elbow and contracts the short distance to move the hand a large distance

Question 12

Pulley

Answer 12

Used to lift things 
Point in the middle of bullseye is like the middle of a lever. Rest of pulley resembles a first class lever

Question 13

Block and tackle

Answer 13

Multiple pulleys used to put together a single unit

Question 14

Wheel and axle

Answer 14

Made of a lever or pulley connected to a shaft

When wheel turns axle turns too.

Question 15

Inclined plane

Answer 15

Turns a small input force into a large output force by spreading the work over a larger distance

Question 16

Wedge

Answer 16

It pushes through wood and breaks it apart

Wedge functions like two inclined plans back to back

Question 17

Screw

Answer 17

An inclined plan wrapped around a cylinder

Examples are jar lids, the normal screw, spiral cases

Question 18

Potential energy

Answer 18

Energy that an object has because of its position, shape or condition

Question 19

Kinetic energy

Answer 19

Energy of a moving object due to its motion

Question 20

Mechanical energy

Answer 20

The amount of work an object because of that objects kinetic and potential energy

Question 21

Elastic potential energy

Answer 21

Energy stored in any type of stretched or compressed elastic material
Example is a spring or bungee cord

Question 22

Non mechanical energy

Answer 22

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

Question 23

Efficiency

Answer 23

The ratio of useful work out to work in

Expressed as a percentage

Question 24

Open system

Answer 24

Exchange energy with space around them

Question 25

Closed system

Answer 25

When the flow of energy in and out of a system is so small it can be ignored?

Question 26

Perpetual motion machine

Answer 26

Theoretical machines designed to keep on going forever without any input of energy