Density

Question 1

What is temperature?

Answer 1

Temperature is a measure of how hot something is

Question 2

List in order of hottest to coldest:
An ice cube
Bunsen burner flame
Your iPad
Liquid nitrogen
The sun

Answer 2

Hottest:
Sun
Flame
iPad
Ice cube
Liquid nitrogen
Coldest:

Question 3

What is heat?

Answer 3

Heat is the flow of energy between objects at different temperatures

Question 4

If you placed an ice cube next to a Bunsen burner flame, which direction would the heat flow?

Answer 4

Flame-> ice cube

Question 5

If you placed an ice cube next to a Bunsen burner, which object will get hotter?

Answer 5

Ice cube because cold-> hot

Question 6

If you placed an ice cube next to a Bunsen burner flame, which would get cooler?

Answer 6

The Bunsen burner hot-> cold

Question 7

When is no heat transferred?

Answer 7

When two objects are the same temperature

Question 8

Why does a hot mug of tea cool down?

Answer 8

It cools down because it has a greater temperature than its surroundings, therefore, it loses heat.

Question 9

How does surface area affect how quickly heat is transferred?

Answer 9

If an object has a larger surface area, the faster the heat energy will flow as there is a greater surface to lose heat from.

Question 10

When will an object float in water?

Answer 10

If it has a lower density than the water.

Question 11

What can the units of density be?

Answer 11

kg/m 3 or g/m 3

Question 12

What is density?

Answer 12

Density is how compact the matter is.

Question 13

How can you work out density?

Answer 13

Density = mass/volume
P=m/v

Question 14

What is heat transfer in terms of conduction?

Answer 14

Conduction is when heat is transferred when particles collide. This happens best through a solid. This is because in a solid the particles are closer together, giving the heat less distance to travel therefore it is easier.

Question 15

When cooking, why do we use metal skewers?

Answer 15

So we can cook the insides of the meat.

Question 16

How does conduction in a metal work?

Answer 16

Metals are better conductors than non-metals. When a metal is heated at one end, the free electrons at the hot end gain kinetic energy and move faster. These electrons diffuse and collide with other free electrons and ions in the cooler part of the metal. As a result, they transfer heat energy to these electrons and ions.

Question 17

What is convection?

Answer 17

Convection is a type of heat transfer in fluids (liquids and gases). Convection 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. The water in the region of the Bunsen burner is heated. It expands, become less dense and rises. It is replaced by the cooler, denser water which surrounds it. The water is in turn heated, expands becomes less dense and rises. A convection current is set up and heat is transferred through the liquid.

Question 18

What is radiation?

Answer 18

Radiation is when heat travels from one place to another as an electromagnetic wave. Any hot object will emit heat radiation- the hotter it is, the more radiation it emits.

Question 19

Why is black a good absorber?

Answer 19

When you wear a black shirt on a hot, sunny day you would feel hotter than if you wore white. This is because black emits infrared radiation from the sun better than white does.

Question 20

How can a system minimise or maximise heat transfer using conduction, convection or radiation?

Answer 20

Insulating materials are bad conductors and so this reduces the heat loss by conduction. The material also prevents air circulating inside the cavity, therefore reducing heat loss by convection. Heat loss through the roof can be reduced by laying loft insulation. This works in a similar way to cavity wall insulation.

Question 21

What is evaporation?

Answer 21

Evaporation is the process by which an element or compound transitions from its liquid state to its gaseous state below the temperature at which it boils; in particular, the process by which liquid water enters the atmosphere as water vapour in the water cycle.