Particle Motion in Gases


  • Particles in a gas constantly moving in random directions with random speeds
  • Increase temperature = transfer energy into thekinetic energy stores of particles
  • Temp of gas is related to the average energy in the kinetic energy stores. Higher temp = higher average energy
  • Increase the temp of a gas = average speed of its particles increases
  • Gas particles move at high speeds = bang into each other = when they collide with something = exert a force (so pressure) on it.
  • In a sealed container = outward gas pressure = total force exerted by all the particles in the gas on a unit area of the container walls
  • Faster particles = more frequent collisions =increase in net force and pressure
  • Increasing temp = increase speed = pressure increases (if volume is constant)
  • Iftemp is constant = increasing the volume of a gas = particles more spread out = hit walls of container less often = gas pressure decreases
  • pV= constant (p = pressure = Pa) (V= volume = m³)
  • pressure of a gas = causes net outwards force at right angles to surface of its container
  • force outside the container = due to pressure of gas around it
  • if a container can easily change its size = any change in these pressures = cause the container to compress or expand
  • transfer energy by applying a force = do work
  • doing work on a gas = increasing internal energy = increasestemperature
  • can do work on a gas mechanically

How long have you…? (present perfect 4) Exercises




Use the information given to create questions beginning with ‘How long…?’

• It is snowing.

• The weather is shining.

• John and Kate are married.

• My brother has gone on holiday.

• My aunty and uncle live in Canada.

• My sister is a teacher.

• I work at the chemist.

• I’ve known Susan since I was a baby.

• Jonathan is learning to speak to Mandarin.




Fill in the missing gaps in the sentences using the present perfect (=has/have + past participle)

• I have known Kate a long time.

• My brother has been playing the piano he was 11 years old.

• My mum and dad on holiday to America. They

gone since last Sunday.

• I Ben and Emma since primary school.

We to the same primary and secondary school.

• My sister learning to speak French because she
is going to France next month.



Use the appropriate words in the missing gaps.

have you lived       lives      to

has been       works        have known

I have bought       have worked.

• My sister in Spain. She is studying Spanish

with her friend Rosie. I Rosie since I was 5.

• Spencer like with Jamie. They have worked

together for 2 years.

• How long in Australia?

• a new dress for prom.

• He to Thorpe park.



Challenge: Create 4 of your own questions beginning with ‘How long……?’








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“Every accomplishment starts 
With the decision to try.” Gail Dever

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