# Physics 1

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• Created by: kelz0209
• Created on: 04-04-14 08:59
What is condensation?
When a gas turns to a liquid.
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Explains what happens during condensation.
Gas cools down- paticles slow down, lose kinetic energy and attractive forces pull particles closer together. Becomes a liquid.
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What needs to happen for condensation to take place?
Water vapour needs to come in contact with a cold surface e.g. glass.
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What is steam?
Invisible water vapour condensing to form tiny water droplets as it spreads to cooler air.
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What is evaporation?
When a liquid turns to a gas- particles escape from a liquid.
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Name 2 ways particles near the surface of a liquid can escape.
1. Particles travelling in right direction to escape liquid. 2. Particles travelling fast enough (enough kinetic energy) to overcome the attractive forces of the other particles in a liquid.
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What happens to the average speed and kinetic energy of the remaining particles, when the fastest particles evaporate?
Decreases.
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When the average particle energy decreases, what happens to the temperature and give an example of how it is useful?
The temperature cools. The cooling effect is useful because you sweat when you exercise or get hot, so the water from the sweat on your skin evaporates and cools you down.
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Why would the rate of evaporation be quicker if the temperature was higher?
At high temperatures, the average particle energy will be higher, so more particles will have enough energy to escape.
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Why would the rate of evaporation be quicker if the density was lower?
Forces between the particles will be weaker, so more particles will have enough energy to overcome these forces and escape the liquid.
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Why would the rate of evaporation be quicker if the surface area was larger?
More particles would be near enough to the surface to escape the liquid.
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Why would the rate of evaporation be quicker if the airflow over the liquid was greater?
Greater airflow means air above the liquid is replaced more quickly, so the concentration in the air will be lower.
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Why would the rate of condensation be quicker if the temperature of the gas was lower?
The average particle energy in the gas is lower, so more particles will slow down enough to clump together and form liquid droplets.
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Why would the rate of condensation be quicker if the airflow was less?
The concentration of the substance in the air will be higher, so the rate of condensation will be greater.
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Why would the rate of condensation be quicker if the density was higher?
Forces between the particles will be stronger. Fewer particles will have enough energy to overcome these forces and will instead clump together and form a liquid.
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To make the rate of condensation faster the temperature of the surface the gas touches has to be ........
Lower
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Name two things that rate of heat energy transfer depends on.
1. Surface area and volume. 2. Type of material.
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Where is the heat energy radiated from an object?
The surface.
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The bigger the surface area, the more infrared waves can be emitted from (or absorbed by) the surface. What does this mean will happen to the transfer of heat?
The transfer of heat will be quicker.
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Why do car or motobike engines have 'fins'?
To increase the surface area, so heat is radiated away quicker, therefore cooling the engine quicker.
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What are heat sinks and give an example of where are they can be found?
Devices designed to transfer heat away from objects they're in contact with, they have fins and a large surface area, so they can emit heat as quickly as possible e.g. computer components.
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What would happen if two objects at the same temperature have the same surface area but different volumes and why?
The object with the smaller volume would cool more quickly, as a higher proportion of the object will be in contact with its surroundings.
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What do objects made of good conductors do to heat energy?
They transfer heat away more quickly than insulating materials e.g. plastic.
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## Other cards in this set

### Card 2

#### Front

Explains what happens during condensation.

#### Back

Gas cools down- paticles slow down, lose kinetic energy and attractive forces pull particles closer together. Becomes a liquid.

### Card 3

#### Front

What needs to happen for condensation to take place?

What is steam?

### Card 5

#### Front

What is evaporation?