7 — Energy

Question 1

Types of energy stores

Answer 1

Kinetic store, gravitational potential store, chemical potential store, elastic potential store, internal store, nuclear store

Question 2

Define energy store

Answer 2

A way in which energy can be kept in a system

Question 3

Work done

Answer 3

Work done by a constant force on a object is the product of the force and the distance moved by the object in the direction of an applied force

Question 4

Define 1J based on work done

Answer 4

1J = work done by a force of one Newton, which moves an object thru a distance of one metre in the direction of the force

Question 5

Gravitational potential energy store

Answer 5

G.p.e. Store is the energy possessed by a body due to its position relative to the ground

Question 6

The principle of conservation of energy

Answer 6

The principle of conservation of energy States that energy cannot be created or destroyed. Energy can be transferred from one store to another. The total energy of an isolated system is constant.

Question 7

Power

Answer 7

Power is defined as the rate of work done or rate of energy transferred.

Greater power -> greater amt of work done during same period of time/ Same amt of work done during shorter period of time

Question 8

Renewable source of energy

Answer 8

Source of energy that can be replaced at a sustainable rate

Question 9

Work done Answ technique

Answer 9

Yes/no work is done. Since a (direction)force is exerted on(x), and (x) moved (direction) in the same direction as exerted force, work is done.

Question 10

Power rating

Answer 10

For every 1s, _J of electrical energy is converted to heat and light

Question 11

Renewable energy sources

Answer 11

1. Biofuels
2. Wind
3. Tides
4. Hydropower
5. Geothermal reservoirs
6. Solar power

Question 12

Non-renewable energy sources

Answer 12

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

Question 13

Biofuels

Answer 13

• renewable energy source (RES)
• widely available on a large scale
• relatively cheap cost of production

Disadvantage:
- env pollution from gs produced

Question 14

Wind

Answer 14

A:
- RES
- no GHG produced

D:
- intermittent power
- noise pollution + loss of habitat for wildlife -> land cleared to build turbines

Question 15

Tides

Answer 15

A:
- RES
- more reliable than wind/sun
- no GHG produced

D:
- high cost of building tidal barrages, turbines n generators
- marine life affected due to alterations of water currents, noise n emission of electromagnetic fields

Ke water -> ke turbine

Question 16

Hydropower

Answer 16

A:
- RES
- no GHG produced
Gpe water -> ke turbine
D:
- high cost
- posb dmg to env due to damming of river

Question 17

Geothermal reservoirs

Answer 17

A:
- RES
- clean source of naturally available energy in internal stores
Ie water -> ke turbine
D:
- release of poisonous gases ->. Env pollution
-not widely available

Question 18

Solar power

Answer 18

A:
- RES
-no GHG produced

D:
- weather-dependent
- solar panels takes up lots of space

Question 19

Fossil fuels

Answer 19

A:
- independent on env factors, more reliable
- relatively cheaper cost of production

D:
- NRES
- gases produced during burning -> env pollution + GW

Question 20

Nuclear fuels

Answer 20

• low carbon energy resource -> lower GHG emissions causing gw
• more reliable in supplying uninterrupted power

D:
- NRES’- risk of accidents + pollution from improper radioactive waste disposal

Question 21

Natural gas

Answer 21

A:
- easy to store
- cheaper than other FF
- large reserves
- less pollution
- reliable

D:
- non-renewable
- reduce GHG
- danger of explosion
- danger of CO poisoning

Question 22

Describe the pathway and energy transfer of the falling ball

Answer 22

Energy in gravitational potential store is transferred mechanically to kinetic store of the ball by weight of ball acting over distance it falls

Question 23

Kinetic energy

Answer 23

Energy a body possessed due to its motion

Question 24

Gravitational potential energy

Answer 24

Energy o a mass due to its position in a gravitational field

Question 25

Efficiency

Answer 25

Ratio of useful energy output over the total energy input and is usually expressed as a percentage

Question 26

Energy

Answer 26

Capacity to do work

Question 27

One watt

Answer 27

Rate of work done or energy conversion of one joule per second

Question 28

State one disadvantage of using wind turbines to produce a high proportion of the electricity in SG. [1]

Answer 28

It is not windy in Singapore / not enough space to build

Question 29

Gravitational potential energy

Answer 29

Gpe is the energy stored in the object due to its vertical height above ground.