Pressure at different depths and heights | Science | Quizalize & Oak National Academy

Starter quiz

Which of the following will increase the pressure produced by a knife being used to cut a rope?
- increasing the force used ✓
- decreasing the force used
- sharpening the knife to decrease the area of contact ✓
- making the knife blunt to increase the area of contact
A raft of weight 400 N floats on the surface of water. What is the size of the upthrust acting on the raft?
- '400 N' ✓
Which of these is the correct equation to calculate pressure?
- $pressure = {force \times area}$
- $pressure = {force \over area}$ ✓
- $pressure = {force + area}$
- $pressure = {force - area}$
A box with a weight of 30 N touches the floor over an area of 0.5 m $^2$ . What pressure does the box produce on the floor?
- 29.5 N/m $^2$
- 30 N/m $^2$
- 30.5/m $^2$
- 60 N/m $^2$ ✓
- 120 N/m $^2$
A pupil pushes downwards with their hand which has a surface area of 60 cm $^2$ . The pressure they produce is 1.2 N/cm $^2$ . What sized force are they pushing down with?
- 50 N
- 60 N
- 61.2 N
- 72 N ✓
Which of the following produces a pressure of one pascal (1 Pa)?
- a force of 1 N acting over an area of 1 cm $^2$
- a force of 1000 N acting over an area of 1 m $^2$
- a force of 1 N acting over an area of 1 m $^2$ ✓
- a force of 10 000 N acting over an area of 10 000 cm $^2$
- a force of 1 N acting over an area of 10 000 cm $^2$ ✓

Exit quiz

Match the key words and phrases to the explanations.
- upthrust
  
  ⇔
  
  a force acting upwards due to pressure differences ✓
- pressure
  
  ⇔
  
  the effect of a force acting over an area ✓
- depth
  
  ⇔
  
  the distance under the surface of a liquid ✓
- atmospheric pressure
  
  ⇔
  
  the pressure caused by the air in the atmosphere ✓
Which of these will increase the maximum weight a raft can support before it starts to sink?
- increasing the weight of the raft
- decreasing the surface area of the raft
- increasing the surface area of the raft ✓
- making the raft out of denser materials
A raft of weight 2000 N and surface area of 4.0 m $^2$ floats on the surface of water. What pressure is the water putting on the raft?
- 0.002 N/m $^2$
- 500 N/m $^2$ ✓
- 1996 N/m $^2$
- 2004 N/m $^2$
- 8000 N/m $^2$
A shark is travelling deeper and deeper into the ocean. Which of the following are correct?
- the pressure decreases with depth
- the pressure increases with depth ✓
- the pressure acts from all directions ✓
- the pressure acts only from above
Sort these statements into order of the change in pressure. Start with the one describing the greatest change in pressure to the one describing the smallest change in pressure.
- 1
  
  ⇔
  
  moving from 1000 m under the surface of the ocean to 1000 m above it
- 2
  
  ⇔
  
  moving from 100 m under the surface of the ocean to 1000 m above it
- 3
  
  ⇔
  
  moving from 100 m under the surface of the ocean to the surface (0 m)
- 4
  
  ⇔
  
  moving from the surface of the ocean (0 m) to 1000 m above it
- 5
  
  ⇔
  
  moving from the surface of the ocean (0 m) to 100 m above it
A magician fills a glass with water and puts a sheet of card on top. They then turn the glass and card over carefully and the water does not fall out. What is the best explanation for this?
- The water has become weightless as the card blocks gravitational forces.
- The water pressure pushing down is about zero as the card has a very small area.
- Air pressure below the card produces a force greater than the weight of water. ✓
- The card is waterproof so the water cannot escape.

Worksheet

Loading worksheet ...

Presentation

Loading presentation ...

Video

Lesson Details

Key learning points

The bigger the surface area of a boat’s hull, the bigger the upthrust on it can be.
Pressure in liquid increases with depth because there is more liquid pushing down.
Pressure in the atmosphere reduces with height because there is less air pushing down.

Common misconception

Pressure is greater at the bottom of a wider container than at the bottom of a narrower one.

Discuss how the force of water in the wider container is acting over a bigger area and refer to pressure = force ÷ area.

Keywords

Upthrust - A force acting upwards due to pressure is an upthrust.
Pressure - The pressure on a surface is the effect of a force acting over an area.
Depth - Depth is the distance under the surface of a liquid.
Atmospheric pressure - Atmospheric pressure is the pressure caused by the atmosphere, this decreases with height.