A balloon will return to its original shape after it has been stretched and a ball will return to its original shape after it has been compressed. A dough- or paste-like substance, for example bread dough or toothpaste, when compressed and stretched will not return to its original shape. Balloons and balls are said to be elastic while a dough or paste is said to be plastic.
A submarine alters its weight by adjusting the amount of air or water in its ballast tanks. This way it can remain at a given depth, rise or sink in the water. The principle behind the submarine’s manoeuvres
can be described as upward force = weight of submarine.
A sea breeze involves the transfer of heat by convection. At the coast during the day the land warms faster than the sea and this causes air over the land to warm and rise; cooler air from over the sea then
moves in to replace the air over the land that has risen. At night the land cools faster than the sea and so the process is reversed.

< means less than, eg 3<4
> means greater than, eg 5>4
> = means greater than or equal to
<= means less than or equal to


1. The elasticity of a balloon . the elasticity of a paste.

A True
B False
C Cannot tell

Answer( )

2. The speed at which land warms is , the speed at which water warms.

A True
B False
C Cannot tell

Answer( )

3. When a submarine sinks, the upward force . the submarine’s weight.

A True
B False
C Cannot tell

Answer( )

4. The sea cools at a rate . than the land.

A True
B False
C Cannot tell

Answer( )


5. When a submarine rises, the upward force . than the submarine’s weight.

A True
B False
C Cannot tell

Answer( )


6. When a submarine rises, the amount of water is , air in its ballast tanks.

A True
B False
C Cannot tell

Answer( )


7. The plasticity of a dough , the plasticity of a ball.

A True
B False
C Cannot tell


Answer( )


8. A dough has # elasticity compared to a paste.

A Probably true
B Probably false
C Cannot tell

Answer( )


9. At night the air temperature over the sea is $to the temperature of the air over the land.

A Probably true
B Probably false
C Cannot tell

Answer( )

30. When a submarine remains at a given depth the weight of the submarine equals the upward force.

A True
B False
C Cannot tell

Answer( )