Starter quiz
- Which of the following show a definition of work or a unit of work?
- J ✓
- N
- force exerted when energy makes an object move
- energy transferred when a force makes an object move ✓
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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 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.
- A gas expands by exerting an average force of 500 N on a piston. This pushes the piston through a distance of 4.0 cm in the direction of the force. The work done by the gas on the piston is ______ J.
- '20' ✓
- When some gas is released from a container, the gas expands rapidly. Which of the following statements are correct?
- The gas cools as it expands. ✓
- The gas heats up as it expands.
- The surrounding air does work on the gas.
- The gas does work on the surrounding air. ✓
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- The volume of a sealed container of gas is halved. Which of the following statements describe what happens to the gas after the decrease in volume?
- The particles take more time between collisions, on average.
- The particles travel less far between collisions, on average. ✓
- The particles collide more often with each cm of the container’s surface. ✓
- The pressure of the gas on the container increases. ✓
- The pressure of the gas in the container halves.
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- A container of gas at a pressure of 80 kN/m has a volume of 0.050 m. What is the pressure when the container expands to a volume of 0.075 m?
- 4.0 kN/m
- 53 kN/m ✓
- 120 kN/m
- 4000 kN/m
- 53 000 kN/m
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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 amount of gas increases, or volume decreases.
- Increasing temperature increases the speed of particles in a gas.
- Pressure × volume = constant (pV = constant).
- When a gas expands, its particles do work on the surrounding air.
- Doing work on a gas can increase its temperature.
Common misconception
Pressure is a weight or a force; and 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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