Topic 1: Energy

Question 1

What are the eight forms of energy?

Answer 1

Thermal, Kinetic, Gravitational Potential, Elastic Potential, Chemical, Magnetic, Electrostatic, Nuclear.

Question 2

What is the calculation for Work Done?

Answer 2

WORK DONE = FORCE x DISTANCE
W = F x D
Joules = Newtons x Metres

Question 3

Define Work Done.

Answer 3

Work done is the product of the force and the distance over which the force is applied.

Question 4

What is the calculation for Weight?

Answer 4

WEIGHT = MASS x GRAVITATIONAL FIELD STRENGTH
W = m x g
Newtons = Kilograms x Newtons per Kilogram

Question 5

What is the calculation for Gravitational Potential Energy (GPE)?

Answer 5

GRAVITATIONAL POTENTIAL ENERGY = MASS x GRAVITATIONAL FIELD STRENGTH x HEIGHT
Ep = m x g x h
Joules = Kilograms x Newtons per Kilogram x Metres

Question 6

What is the calculation for Elastic Potential Energy?

Answer 6

ELASTIC POTENTIAL ENERGY = 1/2 x SPRING CONSTANT x (EXTENSION)^2
Ee = 1/2k x e^2
Joules = Newtons per Metre x Metres^2

Question 7

What is the calculation for Kinetic Energy?

Answer 7

KINETIC ENERGY = 1/2 x MASS x (SPEED)^2
Ek = 1/2m x (v)^2
Joules = Kilograms x Metres per Second^2

Question 8

What is the calculation for Efficiency?

Answer 8

EFFICIENCY = USEFUL ENERGY TRANSFERRED
———————————————–
TOTAL ENERGY SUPPLIED

Question 9

Can an energy transfer be more than 100% efficient?

Answer 9

No, no energy transfer can be more than 100% efficient.§

Question 10

Why do machines waste energy?

Answer 10

Machines waste energy because of friction between their moving parts, air resistance, electrical resistance, and noise.

Question 11

What is the equation for power?

Answer 11

POWER = WORK DONE
———————
TIME

Watts = Joules / Seconds

Question 12

What is another equation for power?

Answer 12

POWER = ENERGY TRANSFERRED
————————————
TIME

Watts = Joules / Seconds

Question 13

One Watt =?

Answer 13

One Watt = 1 joule of energy transferred per second.

Question 14

What is the Conservation of Energy Principle?

Answer 14

Energy can be transferred usefully, stored or dissipated, but can never be created or destroyed.

Question 15

Define Power

Answer 15

Power is the rate of energy transfer or the rate of doing work.

Question 16

Define a powerful machine

Answer 16

A powerful machine is one which transfers a lot of energy over a short amount of time.

Question 17

Define Conduction

Answer 17

Conduction is the process where vibrating particles transfer energy to neighboring particles. It occurs mainly in solid.

Question 18

Define Convection

Answer 18

Convection is where energetic particles move away from hotter to cooler regions.

Question 19

How is energy transferred?

Answer 19

Energy can be transferred mechanically, electrically, by heating or by radiation

Question 20

For a falling object with no air resistance?

Answer 20

Energy lost from the g.p.e. store = Energy gained in the kinetic energy store

Question 21

Equation linking energy transferred to s.h.c.?

Answer 21

Change in thermal energy = mass x s.h.c. x change in temperature
J = kg x J/kgoC x oC

Question 22

How to investigate s.h.c?

Answer 22

Measure the mass of a block and then wrap it in insulating materials to reduce energy transferred from the block to the surroundings.
Insert thermometer and heater. Measure initial temperature and set the p.d. of the power supply to 10v.
As the block heats up, take readings if the temperature and current every minute for 10mins.
Turn off the heater and use P = VI to calculate power.
Then use E = Pt to calculate how much energy has been transferred to the heater.
Plot the graph and find the gradient to work out the s.h.c. through: 1/(gradient x mass of the block)

Question 23

Ways of reducing unwanted energy transfers?

Answer 23

Have thick walls
Use thermal insulation  
          Cavity wall insulation
          Loft insulation
          Double-glazed windows
          Draught excluders around doors and windows

Question 24

Non-renewable energy resources?

Answer 24

Coal
Oil
Natural Gas
They will all run out one day
They all damage the environment
But they provide most of our energy

Question 25

Renewable energy resources?

Answer 25

The sun
Wind
Waves
Tidal
Bio-fuel
Tides
Geothermal
Hydro-electric
They will never run out
Some can be unreliable

Question 26

Wind Power?

Answer 26

Through putting up wind turbines in exposed places
The wind turns the blades, which turns the generator and produces energy
No pollution
Can be noisy
Some say they spoil the scenery
Initial costs are high but no fuel costs and minimal running costs
No permanent damage to the landscape
You cannot increase the power output when faced with increased demand

Question 27

Solar power?

Answer 27

Solar cells generate electric currents directly from sunlight
No pollution
In sunny countries, very reliable but only in the daytime
Initial costs are high but energy is free and little to no running costs
small-scale energy output

Question 28

Geothermal power?

Answer 28

In volcanic areas where hot rocks are near the surface
Source is the slow decay of various radioactive elements
Free energy that’s reliable and with very little damage to the environment
Not many suitable locations

Question 29

Hydro-electric power?

Answer 29

usually requires the flooding of a valley by building a dam
Water is allowed steadily out which powers turbines
No pollution
Big environmental impact
and possible loss of habitat for some species
it can provide immediate responses to an increased demand for energy.
Initial costs are high but no fuel costs and minimal running costs

Question 30

Wave power?

Answer 30

Lots of small wave powered turbines located around the coast
No pollution
But seabed is disturbed and the habitats of marine animal can be destroyed
Fairly unreliable and when the wind drops, waves die out
Initial costs are high but no fuel costs and minimal running costs

Question 31

Tidal power?

Answer 31

By building a tidal barrage that is a dam built across river estuaries with turbines in them
As the tide comes in, it fills up the estuary and the water is then allowed out through the turbines at a controlled speed.
Tides produced by the gravitational pull of the sun and moon
No pollution
Prevents free access by boats, spoiling the view and altering the wildlife’s habitat.
Initial costs are moderately high but no fuel costs and minimal running costs

Question 32

Bio-fuels?

Answer 32

From either plant products or animal dung
and can be burnt to produce electricity or run cars in the same way as fossil fuels.
Supposedly carbon neutral
Fairly reliable, as crops take a relatively short time to grow, but they cannot respond to immediate energy demands
The cost to refine biofuels is very high

Question 33

Non-renewable power?

Answer 33

fossil fuels and nuclear energy are reliable. There’s currently enough to meet current demands and are extracted from the earth at a fast enough rate that the power plants can always have fuel in stock
But they are slowly running out
The setup costs of a power plant can be quite high, the running costs aren’t that expensive and it is cost effective.
They produce CO2 into the atmosphere, adding to the greenhouse effect and contributing to global warming.
Coal and oil can also release sulfur dioxide which causes acid rain
Coal mining spoils the landscape
Oil spillages can cause serious environmental problems
Nuclear power is clean but the waste is dangerous and difficult to dispose of and carries the risk of major catastrophe.