Starter quiz
- Which of the following can be used to describe the motion of particles in a gas?
- random ✓
- constant speed
- typically faster than in liquids ✓
- typically the same speed as in liquids
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- Which of the following show a definition of pressure or a unit of pressure?
- a type of force
- force per unit area ✓
- force per unit volume
- N
- N/m ✓
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- Which of the following are equal to 1 kN?
- 0.001 N
- 0.001 MN ✓
- 1000 mN
- 1000 N ✓
- 1 000 000 N
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- If the particles in a gas are pushed closer together, the pressure of the gas increases. Which of the following explains why?
- Particles collide with each other more often. ✓
- Some of the particles stick together.
- The particles are squashed so they become smaller.
- The particles repel each other more strongly all the time.
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- A table of weight 500 N stands on the floor. The area of contact between the table and the floor is 200 cm. The pressure exerted by the table on the floor is __________ N/cm.
- 0.40
- 2.5 ✓
- 500
- 700
- 1000
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- A sealed container in the shape of a cube contains gas. Which of the following statements are correct?
- pressure of gas = force on one inner face of cube ÷ area of one face ✓
- pressure of gas = force on one inner face of cube ÷ total area of all faces
- The gas exerts pressure because its weight pushes down on the container’s base.
- The gas exerts pressure because its particles exert forces on all inner faces. ✓
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Exit quiz
- Which of the following statements about the particle model are correct?
- It can be used to explain how matter behaves. ✓
- It can be used to predict how matter will behave. ✓
- The model is made of diagrams or animations.
- It says that particles move in liquids and gases but not in solids.
- It says that particles in solids, liquids and gases are always moving. ✓
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- A sealed container of fixed volume contains gas. Which of the following happen when more gas is added to the container?
- The mass of the gas in the container increases. ✓
- The volume of the gas in the container increases.
- The pressure of the gas on the container increases. ✓
- The gas exerts a greater average force on the inside of the container. ✓
- There are more collisions per second between gas particles and container. ✓
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- A child blows air into a balloon. Order the statements to describe and explain what happens.
- 1⇔There are more particles inside, so their collisions become more frequent.
- 2⇔This increases the outward forces exerted by the air on the balloon.
- 3⇔The outward forces are now greater than the inward forces.
- 4⇔This makes the balloon expand, which increases the volume inside it.
- 5⇔The particles inside are now more spread out, so collisions are less frequent.
- 6⇔This decreases the pressure on the inside of the balloon.
- 7⇔Expansion stops when this balances the air pressure outside.
- Which of the following happen when a car tyre is under-inflated, so that there less air in it than when it is correctly inflated?
- The tyre is too hard.
- The tyre wears out unevenly and more quickly. ✓
- The air pressure in the tyre is too low. ✓
- The tyre changes shape more easily. ✓
- There is less contact area between the tyre and road surface.
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- A driver puts air into their car’s tyres when the car is empty. They check that the pressure is correct. If a lot of heavy luggage is now put into the car, which of the following are correct?
- The pressure inside the tyres increases. ✓
- The pressure inside the tyres stays the same.
- The mass of air inside the tyres increases.
- The mass of air inside the tyres stays the same. ✓
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- Which of the following changes would increase the pressure of a gas in a closed container?
- increasing the mass of gas inside ✓
- decreasing the mass of gas inside
- increasing the temperature of the gas inside ✓
- decreasing the temperature of the gas inside
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Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- The pressure of a gas in a container increases if the temperature or the mass of gas increases, or the volume decreases.
- Increasing the temperature increases the average speed of the particles in a gas.
- Increasing the speed of the particles in a gas at a fixed volume increases its pressure.
Common misconception
Pressure is a weight or a force; pressure has a preferred downwards direction in a liquid or gas.
Use the particle model to provide opportunities for pupils to explain the causes of pressure in a gas that is in a container, and to explain how the difference in pressure between inside and outside causes an outward force.
Keywords
Particle model - a scientific model using the idea of moving particles to explain the behaviour of matter
Pressure - caused by a force acting over an area on a surface; it can be calculated using: pressure = force ÷ area
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