Unit 1: Heating Houses

Question 1

What does a thermogram do?

Answer 1

It uses colour to show temperature. Hottest areas are white coldest are blue or black

Question 2

In what direction is energy transferred?

Answer 2

From a hotter to a colder body.

Question 3

What happens when temperature increases?

Answer 3

The average kinetic energy of the particles increases.

Question 4

What is heat?

Answer 4

It is a measurement of internal energy. Measured on an absolute scale.

Question 5

What is specific heat capacity?

Answer 5

The energy needed to raise the temperature of 1kg by 1•c
Measured in (J/kg•c)
When heated temperature rises energy is transferred.

Question 6

What is temperature?

Answer 6

Measure of hotness on an arbitrary scale measured in •c

Question 7

Calculate the energy transferred when 30kg of water cools from 25•c to 5•c

Answer 7

ET= 30 x 4200 x (25-5) = 30 x 4200 x 20

= 2 520 000 J or 2520 KJ

Question 8

What is specific latent heat?

Answer 8

The energy needed to melt or boil 1 KJ of the material. 
Measured in ( J/kg )
When heated it changes state energy is transferred but the temperature remains constant.

Question 10

Calculate the energy transferred when 2.5 kg of water changes from solid to liquid at 0•c

Answer 10

ET= 2.5 x 340 000

= 850 000 J or 850 KJ

Question 11

Why is there no change in temperature?

Answer 11

There is no change in temperature because when a substance changes state energy is needed to break the bonds that hold the molecules together.

Question 16

What is the specific heat capacity equation?

Answer 16

ET= mass X specific heat capacity X temperature change

Question 17

What is the specific latent heat equation?

Answer 17

ET= mass X specific latent heat