Science Exam

Front 1

How close are atoms & molecules packed together in solids?

Back 1

Very close together.

Front 2

How close are atoms & molecules packed together in liquids?

Back 2

Close, but not as close as in solids

Front 3

How close are atoms & molecules packed together in gases?

Back 3

Far apart.

Front 4

Thermal energy is transferred by?

Back 4

Conduction.

Front 5

What is conduction?

Back 5

When T.E is transferred because objects are touching each other.

Front 6

What is "the heat cycle" called?

Back 6

Convection Current.

Front 7

How does the convection current work?

Back 7

Hot air rises from a heat source and rises in the air until warm air sinks and turns into cold air because of a cool source and the cool air falls and spreads back to the heat source.

(Hot air rises, cold air sinks)

Front 8

Each circulation pattern is called?

Back 8

A convection cell.

Front 9

How do you calculate density?

Back 9

MASS
VOLUME

(D=M/V)

Front 10

Example for Density:

Which glass of water with the same volume is more dense? Cold or hot?

Back 10

Cold. Because hot water water occupies more space because the molecules vibrate faster than in the cold water.

Front 11

Everything floats if you have..?

Back 11

An overall density of smaller than 1 g/cm3

Front 12

Which one has more mass?

Salt or fresh water?

Back 12

Salt water because it has H2O molecules as well as Na+ and Cl- ions.

Front 13

What about if the density is exactly 1? g/cm3

Back 13

The object will go halfway into the water

Front 14

Is water a good conductor of heat or not?

Back 14

Water is good at absorbing heat but not very good at conducting it.

Front 15

Where else can a convection current appear?

Back 15

In liquids. ( E.g when water boils)

Front 16

Where can a convection current not appear?

Back 16

In solids.

Front 17

Why do we get a convection current?

Back 17

Because of differences in fluid densities

Front 18

Differences in temperature cause..?

Back 18

..Differences in density.

Front 19

You have hot & cold water. Which one flows on top of what?

Back 19

Hot on top of cold.

Front 20

What is the definition of convection?

Back 20

Convection is the transfer of thermal energy via the movement of a group particles that have different densities caused by differences in temperature.

Front 21

How can we reduce heat loss through windows?

Back 21

Double glazing. (Windows with 2 panes of glass)

Front 22

Where is the best place to put a room heater?

Back 22

Near the floor.

Front 23

Why is the freezer placed at the top in fridges?

Back 23

Because cold air from the freezer sinks, and it will keep the fridge cool.

Front 24

What is a key temperature?

Back 24

4°C.

Front 25

What happens once you have 4°C?

Back 25

The molecules start to expand again (Increase in volume) as the water continues to cool.

Front 26

Ice takes up more space than..?

Back 26

..Liquid water.

Front 27

Ice takes up more space than liquid water. This causes problems for pipes in the winter. Why?

Back 27

When water freezes it expands with lots of force.

Front 28

If water continued to contract what would happen to a lake during winter?

Back 28

The whole lake would freeze solid, which can harm the animals.

Front 29

What shape, volume, flow and compression do solids have?

Back 29

Shape: Definite
Volume: Fixed volume

Flow: No flow

Compression: Hard to compress

Front 30

What about liquids?

Back 30

Shape: Take shape of container

Volume: Fixed volume

Flow: Flow (Fluid)
Compression: Hard to compress

Front 31

What about gases?

Back 31

Shape: Take shape of container

Volume: Takes volume of container

Flow: Flow (Fluid)
Compression: Easy to compress

Front 32

Which way will heat ALWAYS flow?

Back 32

From hot to cold.

Front 33

Why do you burn your hand while holding a metal object?

Back 33

Because of conduction.

Front 34

What does temperature mean?

Back 34

Temperature is the measure of how fast atoms & molecules move on average.

Front 35

What do thermometers do?

Back 35

They measure how fast atoms & molecules move on average.

Front 36

What does thermal expansion mean?

Back 36

When a substance absorbs heat it generally expands.

Front 37

What does kinetic energy mean?

Back 37

Kinetic energy is the energy of motion

Front 38

What is a conductor?

Back 38

A material that heats well.

Front 39

What is an insulator?

Back 39

A material that conducts heat poorly.

Front 40

What are some good conductors?

Back 40

Metals.

Front 41

What are some good conductors of insulators?

Back 41

Wood, plastic etc.

Front 42

What is the meaning of heat?

Back 42

Heat is a form of energy transfer which causes atoms & molecules to move faster.

Front 43

What does thermal equilibrium mean?

Back 43

Once all the molecules have roughly the same kinetic energy.