In an experiment John uses his thumb to press a one Namibian dollar coin into a

Question

ball of plasticine.
He uses the same force to press the coin on the edge and then on its flat surface.
The diagram shows the result.

Which statement explains the aim of the experiment?
A to demonstrate the influence of force on pressure
B to demonstrate the influence of mass on pressure
C to demonstrate the influence of surface area on pressure
D to demonstrate the influence of volume on pressure

1.2 Which type of power station uses the gravitational potential energy of water to
generate electricity?
A geothermal
B hydroelectric
C nuclear
D wind

1.3 Which property makes liquid mercury the best liquid to use in a liquid-in-glass
thermometer over coloured alcohol?
A It does not freeze at 0°C.
B It does not stick to the glass.
C It is relatively cheap.
D It not toxic and poisonous.

1.4 The diagram shows an uncalibrated mercury-in-glass thermometer.

At 0°C the length of the mercury column is at 4 cm mark. At 100°C the length of the
mercury column is at 80 cm.
What is the length of the mercury column at 40°C?
A 26.4 cm
B 30.4 cm
C 34.4 cm
D 60.8 cm

Answer 1

Here are the answers to your questions:

1.1 Which statement explains the aim of the experiment?

• C to demonstrate the influence of surface area on pressure
  This choice is correct because pressing the coin on the edge and flat surface illustrates how the surface area affects pressure when the same force is applied.

1.2 Which type of power station uses the gravitational potential energy of water to generate electricity?

• B hydroelectric
  Hydroelectric power stations utilize the gravitational potential energy of falling or flowing water to generate electricity.

1.3 Which property makes liquid mercury the best liquid to use in a liquid-in-glass thermometer over coloured alcohol?

• B It does not stick to the glass.
  Mercury's ability not to adhere to the walls of the glass allows for more accurate readings and better visibility of the liquid's position.

1.4 What is the length of the mercury column at 40°C? To find the length of the mercury column at 40°C, you can use linear interpolation between the 0°C and 100°C readings. If 0°C corresponds to 4 cm and 100°C corresponds to 80 cm:

• The difference in temperature is 100 °C - 0 °C = 100 °C.
• The difference in length is 80 cm - 4 cm = 76 cm.
• Therefore, the increase in length per °C is 76 cm / 100 °C = 0.76 cm/°C.

For 40°C:

• The increase from 0°C to 40°C is 40 °C * 0.76 cm/°C = 30.4 cm.
• Adding this to the original 4 cm gives 4 cm + 30.4 cm = 34.4 cm.

Thus, the answer is:

• C 34.4 cm