4 What have I learned about motion and pressure?

Summary: Tags: science oxford-science student-book-7 physics Created: 2026-05-19 Last Updated: 2026-05-19

In this chapter, you have:

• learned how Motion graphs show how the Speed of an object changes with time
• used distance and time to calculate speed when it is constant, or calculated speed using a motion graph
• used the particle model to explain gas Pressure
• learned that gas pressure increases with increased temperature and decreased volume
• learned that atmospheric pressure and liquid pressure both increase as you go ʻdeeperʼ
• calculated the pressure on a solid surface using force and area
• calculated the moment (or turning effect) of a force around a pivot using force and distance
• found out that if an object is balanced, the moments about a pivot are equal.

Journey through motion and pressure What do I already know? - Speed

• Forces
• Drag forces and Friction
• Balanced and Unbalanced Forces This chapter - 4.1 Speed
• 4.2 Motion graphs
• 4.3 Pressure in gases
• 4.4 Pressure in liquids
• 4.5 Pressure on solids
• 4.6 Turning forces What comes next? - Forces and interactions
• Speed and distance–time graphs
• Acceleration and speed–time graphs
• Energy stores and transfers
• Work and power

Figure 3

1. Here are some units. Write down the units of speed. m/sm s hmphkm/skm (3 marks)
2. You can make a hole in a piece of wood if you hit in a nail with a hammer. If you hit the wood with the hammer, it does not make a hole. Choose the best explanation for this from statements A–C. The area of the nail is much smaller, so the pressure is smaller.The area of the nail is much smaller, so the pressure is bigger.The area of the hammer is bigger, so the pressure is bigger. (1 mark)
3. Figure 1 shows a graph of a person riding their bike. Figure 1 Full text alternative to the content State the letter of the part where the person was: stationary (still) (1 mark)moving fastest. (1 mark)Calculate the speed from 0 to A. (3 marks)Describe the cyclist’s motion at points B, C, and D. (3 marks)
4. State the angle between the direction that liquid pressure acts and the surface. (1 mark)Explain, in terms of pressure, why you have to hold a balloon to keep it underwater. (2 marks)Suggest and explain what would happen to the force you need to exert (apply) on the balloon if it were smaller. (2 marks)
5. Calculate the pressure of a person with a Weight of 700 N standing on a foot of area 200 cm2. (4 marks)Describe and explain what happens to the pressure if they stand on two feet instead of one. Do not use a calculation in your answer. (2 marks)Another person exerts a bigger pressure even though their weight is the same. Suggest why. (1 mark)
6. Look at Figure 2 of an arm holding a phone. The phone has a weight of 1.5 N. Figure 2 Calculate the moment of the force exerted by the phone. (2 marks)Calculate the force that the muscle exerts to keep the phone in Equilibrium. (2 marks)Explain why the force exerted by the muscle is much greater than the weight of the phone. (2 marks)
7. You buy a bag of crisps in an airport. After your aeroplane takes off, you take the crisps out of your rucksack. Explain in detail why the bag of crisps has expanded. (6 marks)
8. Look at Figure 3. A person carries a plank of wood so that it balances on their shoulder. Figure 3 Explain why the plank is balanced. (2 marks)The person moves the plank away from its position so there is more plank in front than behind. Suggest and explain, in terms of moments, how the person can balance the plank now . (3 marks)