TOPIC 3 - CONSERVATION OF ENERGY

Question 1

What is GPE?

Answer 1

gravitational potential energy is energy stored in because of an object’s position in a gravitational field. When object moves upwards, stores more GPE

Question 2

What is KE?

Answer 2

kinetic energy is energ stored in moving objects

Question 3

Calculating KE?

Answer 3

0.5 x mass x velocity^2

Question 4

Calculating GPE?

Answer 4

mass x g x height

Question 5

What affects GPE

Answer 5

• mass of object
• strength of gravity
• how far object moves up

Question 6

What affects KE

Answer 6

• mass
• speed

Question 7

What is conservation of energy?

Answer 7

Energy cannot be created or destroyed, only transferred between stores. Total energy transferred by system = energy inputted into system.

Question 8

What happens in a closed system of energy?

Answer 8

there can be energy transferse but no net change to total energy in that system.

Question 9

How is energy dissipated?

Answer 9

Energy dissipates when energy is transferred as heat energy, then transferred to surroundings, often caused by friction. This is wasted energy.

Question 10

How is wasted energy reduced?

Answer 10

1. Lubrication reduces friciton on parts that rub together, reducing dissipation of heat energy.
2. Insulation prevents dissipation of wanted heat.

Question 11

How can you keep a building warm?

Answer 11

1. Build house out of insulating material e.g. straw bale
2. Build a cavity wall - 2 walls with gap between them. Thickness of material affects the rate which energy is transferred through material. Cavity wall increases its thickness, decreasing rate of energy transfer. The air between wall is an insulator so less energy escapes.

Question 12

What is efficiency

Answer 12

How good a machine is at transferring energy into useful forms

Question 13

How to calculate efficiency

Answer 13

Efficiency = useful energy transferred by device/total energy supplied to device
number between 0-1

Question 14

How to increase efficiency

Answer 14

1. Reducing friction
2. Reducing electrical resistance
3. Reducing air resistance
4. Reducing noise

Question 15

What is a renewable energy source

Answer 15

source that replenishes faster than being used

Question 16

WHat is non renewable energy source

Answer 16

source that is used quicker than made

Question 17

Name some non-renewable resources

Answer 17

1. Fossil fuels
2. Natural gases
3. Nuclear fuels

Question 18

Name some renewable resources

Answer 18

1. Solar energy
2. Hydroelectricity
3. Wind turbines
4. Tidal power
5. Bio-fuels

Question 19

Advantages + disadvantages of fossil fuels

Answer 19

+ Easy to store so used in vehicles and engines

• Produces CO2

Question 20

Advantages + disadvantages of natural gases

Answer 20

+ Burning these emit less CO2 than other fossil fuels

Question 21

Advantages + disadvantages of nuclear fuels

Answer 21

+ Nuclear power stations don’t emit CO2

• Waste that they produce is radioactive and expensive to dispose of safely
• Consequence of power station breaking can be catastrophic

Question 22

Advantages + disadvantages of solar energy

Answer 22

+ Renewable

• not available at all times, only when sunny

Question 23

Advantages + disadvantages of hydroelectricity

Answer 23

+ available at all times

Question 24

Advantages + disadvantages of wind turbines

Answer 24

+ renewable

• wind conditions have to be not too slow or fast
• spoils landscape

Question 25

Advantages + disadvantages of tidal power

Answer 25

+ time it is available is predictable
+ renewable

• not available at all times

Question 26

What are bio-fuels

Answer 26

Producing energy by burning animal wastes/plants

Question 27

Advantages + disadvantages of bio-fuels

Answer 27

+ said to be carbon-neutral because they release same amount of CO2 they took from atmosphere when plants grew.

• Not completely carbon neutral as energy is required in other processes e.g. transport