5.11 Starter
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· You're looking at smoke particles in air under a microscope
· They appear to be jiggling about
· Why?
· (Don't worry if you can't work this out straight away - Albert Einstein was the bloke who eventually explained what's happening here!)
· 5.11 understand the significance of Brownian motion
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| <<Video - Model of Brownian motion.wmv>> | ||
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Model 1
· What does the red puck represent?
· What do the metal balls represent?
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| <<brownian_motion.swf>> | ||
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Model 3
· What do the "smoke" particles look like?
· Why are they moving?
· What do the "air" particles look like?
5.11 explained
28 October 2011
11:10
Model 1
· What does the red puck represent?
o The large, visible smoke particle
· What do the metal balls represent?
o The small, not visible air particles
Model 2
· What do the small red particles represent?
o The small, not visible air particles
· What does the large blue particle represent?
o The large, visible smoke particle
· What does the view on the left of the screen represent?
o The view through the microscope lense
· Why can‘t you see the red particles in this view?
o They are too small to see
Model 3
· What do the "smoke" particles look like?
o They are the 5 large, sand coloured particles
· Why are they moving?
o Small, fast moving air particles are colliding with the smoke particles and making them move
· What do the "air" particles look like?
o They are the numerous, small, white particles
5.11 Questions
1. Draw the path of a smoke particle in air (3 marks)
Start |
Finish |
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2. Explain what is meant by Brownian Motion of smoke particles in air and how it provides evidence for air particles (4 marks)
Brownian motion is the random motion of a particle. As for this ,the smoke particle has a random motion. As (invisible) air molecules collide with the smoke particle, they push it about in different directions at random.
Answer
• We can see the large smoke particles
• We can’t see the much smaller air particles
• But the smoke particles move when the air particles collide with them
• So the movement of the smoke particles is evidence for the existence of air particles
3. What change would you expect to see in the movement of the smoke particles if the air was cooled down? Why? (2 marks)
Slow movement for the smoke particle because the (invisible) air particles have less kinetic which means less vibration so it would collide to the smoke particle less often.
Answer
• The smoke particles would move slower
• Because the air particles are moving slower and hitting them with less force
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