making use of energy

Question 1

what is density

Answer 1

how much mass a substance has per unit of its volume

Question 2

density equation

Answer 2

density= mass divided by volume

Question 3

how do we find mass of a solid

Answer 3

weigh it

Question 4

how do we find mass of a solid

Answer 4

weigh it

Question 5

how do we find volume or a regular and irregular solid

Answer 5

regular- length x width x height

irregular- eureka can and measuring cylinder, volume of water that falls into measuring cylinder when solid is added to eureka can is exactly equal to that of the solid

Question 6

how do we find density of a liquid

Answer 6

weigh the water to find the mass
the divide the mass by the amount of liquid you weighed (volume)
(larger the volume often means it’s more accurate because it minimises the effects of uncertainty )

Question 7

what is conduction

Answer 7

when vibrating particles transfer energy to neighbouring particles

Question 8

what is thermal conductivity w examples

Answer 8

how well energy is transferred by conductions
metals have high thermal conductivity
plastics have low thermal conductivity they are insulators

Question 9

what is convention

Answer 9

convention occurs when particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy.

Heat energy is transferred from hot places to cooler places bc Liquids and gases expand when they are heated.

Question 10

how is heat lost in a home and where

Answer 10

heat is lost as it is higher inside than outside it’s travels out by conduction convection and radiation through roof door windows walls and floor

Question 11

how does double glazing reduce heat loss

Answer 11

double glazing bad a layer of trapped air in the gap
trapped air is a good insulator and will reduce heat loss by conduction
air is trapped so it can’t move around reducing heat loss by convection

Question 12

what is an insulator

Answer 12

a material which does not easily allow heat and/or electricity to pass through it

Question 13

loft insulation

Answer 13

uses material with lots of small holes to trap air reducing heat by conduction bc it’s a good insulator
and reducing heat loss by convection bc the air can’t move

Question 14

payback time calculation

Answer 14

payback time= installation cost divided by the annual savings

this gives the number of years until it’s payed back