6.1.2 Conservation and dissipation of energy

Question 1

Energy can be?

Answer 1

transferred usefully, stored, or dissipated, but cannot
be created or destroyed

Question 2

what happens when there is energy transfers in a closed system?

Answer 2

there is no net change to
the total energy.

Question 3

In all system changes energy is?

Answer 3

dissipated, so that it is stored in less
useful ways. This energy is often described as being ‘wasted’.

Question 4

explain ways of reducing unwanted
energy transfers on a moving object/vehicle

Answer 4

1)lubrication- reduces the friction between the moving parts of a machine
2)using wheels-decreases the friction between an object and the surface over which it is moving
3)making vehicles streamlined reduces the amount of air resistance exerted on them

Question 5

explain a way of reducing unwanted energy transfer in cables

Answer 5

using low-resistance cables in an electric circuit reduces the amount of energy dissipated as heat

Question 6

the use of thermal insulation in a build reduces unwanted energy transfer. how?

Answer 6

reduces the rate at which thermal energy is transferred from it

Question 7

The higher the thermal conductivity of a material the higher?

Answer 7

the rate of energy transfer by conduction across the material

Question 8

what is one way to reduce energy loss in a house?

Answer 8

use cavity walls insulation(double wall with gap in the middle), polystyrene foam in these gaps we can reduce the rate of loss of heat energy from the house

Question 9

why is polystyrene foam used in these gaps?

Answer 9

an excellent insulator which means that it is a pure conductor of thermal energy ,it has a low thermal conductivity.

Question 10

single glazed windows have?

Answer 10

high thermal conductivity

Question 11

what else can reduce loss of heat energy?(windows)

Answer 11

double or triple glazed windows can reduce the loss of heat energy as they have a low thermal conductivity

Question 12

the large amount of energy that can be lost through the roof of a house can be reduced by the?

Answer 12

installation of a loft which reduces the rate at which thermal energy passes through

Question 13

what is a final way you can reduce the rate of thermal energy transfer?

Answer 13

build house with thick walls

Question 14

efficiency, units + how it can be written?

Answer 14

has no units , can be written as a decimal(0-1) or percentage(0-100%)

Question 15

describe ways to increase the efficiency of an intended energy transfer.

Answer 15

-use a lid
-plastic walls
-streamlining the shapes of moving objects
-reducing friction by lubricating parts

Question 16

The main energy resources available for use on Earth include:

Answer 16

fossil fuels (coal, oil and gas), nuclear fuel, bio-fuel, wind, hydroelectricity, geothermal, the tides, the Sun, and water waves

Question 17

what is a renewable energy resource?

Answer 17

A renewable energy resource is one that is being (or can be) replenished as it is used

Question 18

what do uses of energy resources include?

Answer 18

transport, electricity
generation and heating.

Question 19

what energy resources are renewable?

Answer 19

biomass, tidal, hydroelectric, wind, solar, geothermal,

Question 20

fossil fuels (non-renewable) are cheap and convenient but release?

Answer 20

greenhouse gases when burnt such as carbon dioxide which contribute to global warming

Question 21

fossils fuels can release sulphur dioxide which can cause ?

Answer 21

acid rain and breathing problems in humans

Question 22

nuclear (non-renewable)

Answer 22

-radioactive waste they produce has to be stored carefully
-risk of nuclear meltdown
-uranium and plutonium are used as he sources of energy in nuclear power stations

Question 23

biomass (renewable)

Answer 23

-the heat released when biofuels are burnt is sued to generate electricity on a small scale or heat buildings directly
-biomass is carbon neutral (absorb coz from the atmosphere when growing + release it again when burnt)

Question 24

tidal (renewable)

Answer 24

-can produce large amounts of electricity in a reliable way
-expensive to build

Question 25

hydroelectric (renewable)

Answer 25

-produces a large amount of electricity without release of co2 ina reliable way
negative:
-people have had to move homes, wildlife destroyed

Question 26

wind (renewable)

Answer 26

-higher the wind speed, the greater the rate at which kinetic energy will be converted to electrical energy inside the generator of a wind turbine

advantage:
-renewable , clean , doesn’t release pollutant gases
disadvanatge:
-can be unreliable –> weather dependent
-environemntal and visual impact

Question 27

solar (renewable)

Answer 27

sunlight that falls in a solar cell is directly used for the generation of electricty

Question 28

geothermal (renewable)

Answer 28

-clean and renwable
-involves use of water or steam which is heated naturally by processes within the earth’s crust