Heat Transfer

Question 1

4factors which affect how much radiation an object emits

Answer 1

• temp diff to the surroundings
• surface area
• colour
• surface type

Question 2

how is heat energy transferred through water in a kettle

Answer 2

by convection

Question 3

3 factors which affect evaporation of a liquid

Answer 3

• surface area of liquid
• temp of surroundings
• the draught

Question 4

what affect does evaporation have on an object

Answer 4

a cooling effect

Question 5

how is the rate of evaporation and the temp. of an object linked

Answer 5

the faster the evaporation the faster the temp. fall of the object the liquid is evaporating from

Question 6

why does evaporation cause a cooling effect

Answer 6

particles with greatest energy escape force of attraction between particles in a liquid and evaporate. This leaves owe riddles with on average a lower energy hence a cool or liquid

Question 7

why does the inside of a vacuum flask have a shiny coat

Answer 7

shiny surfaces are bad emitters of radiation so help keep liquids inside warm

Question 8

why is a gas a bad conductor

Answer 8

there are no free electrons

Question 9

why does an elephant find it hard to stay cool

Answer 9

it has a huge volume compared to surface area. This is why it flaps its ears and sprays water on itself. Also it can’t sweat.

Question 10

describe how heat energy is transferred in copper wire

Answer 10

by conduction