4.3.3.3 Increasing the Pressure of a Gas (physics only)

Question 1

Work:

Answer 1

transfer of energy by a force

Question 2

What does doing work on a gas do?

Answer 2

• doing work on a gas increases the internal energy (as a force has been applied on the gas energy has been transferred to the particles - internal energy includes the kinetic and potential energy of the gas particles) and can cause an increase in the temperature of the gas
• the temperature of a gas is related to the average kinetic energy of the particles and as we have increased the kinetic energy of the particles, we have increased the temperature of the gas

Question 3

Why do bicycle pumps get warm?

Answer 3

• pumps can get warm when they are used to inflate a tyre
• because work is being done on the gas increasing its internal energy

Question 4

What has happened if a force compresses a gas?

Answer 4

if a force compresses a gas work has been done on the gas (there is a transfer of energy to the gas)

Question 5

What happens when a gas is compressed or expanded?

Answer 5

• when a gas is compressed its temp increases as the gas molecules gain KE e.g. when air is compressed into a bike tyre from a bike pump it becomes hotter
• when a gas expands its temperature decreases e.g. the gas from an aerosol deodorant feels cold

Question 6

How can you increase a substances internal energy?

Answer 6

• do work on gas particles to transfer energy by a force to increase kinetic energy which increases internal energy
• heat substance to increase kinetic energy which increases internal energy

Question 7

How can gases do work on an object?

Answer 7

gas can do work on an object by applying a force to the object transferring energy to the object and decreasing its own internal energy