WeyPhys KS3 Pressure

Pressure = Force/ (a)  

What are the units of pressure?

• N m²

• N / m

• N m

• N / m²

What unit for pressure is equal to 1N/m²

• Gauss

• Hertz

• Tesla

• Pascal

A Force of 200N acts on an area of 50cm². What pressure does this cause?

• 4 N/cm²

• 1000 N/cm²

• 150 N/cm²

• 250 N/cm²

A force of 15,000 N acts on an area of 0.2m². What pressure does this cause?

• 750 Pa

• 7,500 Pa

• 75,000 Pa

• 750,000 Pa

A car which weighs 20,000 N presses equally down on 4 tyres, each with a contact acre of 0.02 m². What is the pressure in each tyres?

• 1,000,000 Pa

• 400 Pa

• 250,000 Pa

• 100,000 Pa

Why is the pressure at the bottom of a column of liquid higher than at the top?

• The water at the bottom is much denser than at the top.

• The air pressure is lower at the bottom.

• Because of the weight of all the liquid above it

• Because some water evaporates from the top surface

Which of these tubes has the greatest pressure at the bottom?

• D because the shape narrows lower down

• The pressure is equal at the bottom in all of them.

• C as it contains the greatest volume and weight

• A and C as the tubes only push sideways not upwards.

What causes pressure in gases?

• Collisions between the gas molecules and each other and the container walls.

• Electrostatic repulsion between the gas molecules.

• Chemical reactions between gas molecules releasing thermal energy.

• Gravitational attraction due to the Earth's mass

Why does water boil at 71° C at the top of Mount Everest?

• Because there is a much lower air-pressure there.

• Because water molecules escape from the liquid surface more easily there.

• The air pushes with less force on the water's surface.

• All 3 of these reasons.