Energy

Question 1

Energy is a concept central to all of what?

Answer 1

science

Question 2

a combination of what make up the universe?

Answer 2

matter and energy

Question 3

matter is

Answer 3

substance

Question 4

energy is

Answer 4

abstract, can’t be seen, smelled or felt

Question 5

The idea of energy was unknown to who?

Answer 5

Newtron

- existance was debated

Question 6

persons, places and things have energy but we usually observe energy when it is

Answer 6

being transffered or transformed

Question 7

if WORK is to be done what do things must occur

Answer 7

1) Application of force
2) Movement of something by that force
- Displacement must occur for work to occur

Question 8

one joule of work is done when what happens?

Answer 8

a force of 1 newton is exerted over a distance of 1 metre

Question 9

Power is..

Answer 9

the rate at whitch work is being done on an object

Question 10

Power is vector or scalar? What’s its unit?

Answer 10

Scalar; Joules/Seconds = Watts (W)

Question 11

One watt of power is expended when what happens?

Answer 11

1 joule of work is done in 1 second

Question 12

typically engines/motors are rated in

Answer 12

horsepower and elctricity in watts

Question 13

1 HP =?

Answer 13

750 Watts (W)

Question 14

Energy can take many forms. Mechanical energy is a form of energy due to (2)

Answer 14

a) the relative position of interacting bodies - Potential Energy (PE)
b) due to their motion - kinetic energy

Question 15

Unit for work and energy

Answer 15

Joules

Question 16

Potential Energy (5)

Answer 16

• an object may store energy because of its postition relative to some other object
• in this stored state it has the potential to do work
• work is required to elevate objects against Earth’s gravity - gravitation potential energy
• Gravitation potential energy = weight X height
  PE = m(g) X h

Question 17

Kinetic Energy (5)

Answer 17

• one of the kinds of energy into which PE can change into
• can be reffered to as energy of motion
• depends on an object’s mass and speed
• can only be 0 or positive
  KE = 1/2 m (v^2)

Question 18

Work energy theorem

Answer 18

the work energy theorem states that the work done on a system (net work) equals the energy changes

W = Delta KE
= KE (final) - KE (initial)
= 1/2m (v^2) - 1/2m (v^2)

Question 19

Law of Conservation of Energy

Answer 19

Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes

Question 20

In a closed system the total amount of energy at the start is ___ as the total amount of energy at the end

Answer 20

the same

Question 21

Law of Conservation of Energy equation

Answer 21

KE (initial) + PE (initial) = KE (final) + PE (final)
or
KE (initial) + PE (initial)= KE (final) + PE (final) + heat

Question 22

Machines are devices for what?

Answer 22

multiplying forces or simply changing the direction of forces
- every machine is the Conservation of Enery Concpet

Question 23

2 examples of common machines

and how they change direction or multiply the force

Answer 23

• lever - pulley

- by giving up distance

Question 24

Machine lever/pulley equation

Answer 24

(Force X Distance)input = (Force X Distance) output

Question 25

Efficiency

Answer 25

• represents the percent of work put into a machine that is converted to useful work output

Question 26

Efficiency equation

Answer 26

efficiency = (useful energy output) / (total energy input) X 100

Question 27

What would happen in an idea machine?

What happens in reality?

Answer 27

Idea: 100% work input appears as work output
Reality: Doesnt happen because thermal energy is dissipated

Question 28

What is the graveyard of kinetic energy

Answer 28

thermal energy

Question 29

Sources of energy in the world

Answer 29

majority of the world’s energy - fossil fuels
- then nuclear
then non-sustainable biomass
- the rest s a mixture of renewable (geothermal, solar, wind etc.)

Question 30

List 5 sources of energy

Answer 30

any of the following

- fossil fuels, geothermal, nuclear fission, solar energy, wind energy, hydroelectric power

Question 31

heat is a type of

Answer 31

energy transfer

Question 32

Kinetic molecular theory (KMT) is based on what assumption?

Answer 32

the assumption that matter is made up of many tiny particles that are always in motion. In a hot body, the particles move faster, and thus have a higher energy than in a cooler body

Question 33

Using the KMT we say temperature is

Answer 33

the average kinetic energy of particles in a material

Question 34

Heat (Q) is

Answer 34

the energy that flows from a substance of hot temp. to a substance of cold temp

Question 35

specific heat capacity (c)

Answer 35

the quantity of heat per unit of mass required to raise the temp by 1 degree celcius.

• every material has its own specific heat capacity
• it is a property of the material

Question 36

Conservation of Energy and Equilibrium

Answer 36

• when two materials transfer heat to each other all the heat that one material gains comes from the heat the other material loses
• when two materials are in contact long enough they will eventually reach thermal equilibrium which means they will have the same temp
• heat will transfer from hot to cold until thermal equilibrium is reached

Question 37

Elastic collision

Answer 37

• a collision in which colliding objects rebound without lasting deformation or the generation of hear
• both momentum and kinetic energy are conserved

Question 38

inelastic collision

Answer 38

a collision in which the colliding objects become distorted, or generate heat and possibly stick together

• momentum is conserved
• kinetic energy is not conserved