Particle Model & Pressure (AQA GCSE Physics): Flashcards
Exam code: 8463
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- FrontKinetic Theory
Define Brownian motion.
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Cards in this collection (24)
Define Brownian motion.
The random motion of tiny particles in a fluid.
Define pressure, in the context of a gas.
The force exerted per unit area of the container.
How is the temperature of a gas related to the average kinetic energy of its molecules?
The higher the temperature, the higher the average kinetic energy of the molecules, and vice versa.
What happens to the average speed of gas molecules as the temperature of the gas increases?
The average speed of the molecules increases.
Molecules in a gas are in constant ______ motion at high speeds.
Molecules in a gas are in constant random motion at high speeds.
True or False?
At a constant volume, increasing the temperature of a gas decreases its pressure.
False.
At a constant volume, increasing the temperature of a gas increases its pressure.
Why does heating a gas at constant volume increase its pressure?
The molecules travel at a higher speed, so they collide with the container walls more often, creating an increase in pressure.
Give two things that a gas molecule undergoing random motion can collide with.
The walls of its container, and other molecules.
Define Boyle's Law.
For a fixed mass of gas held at constant temperature, pV = constant, meaning pressure and volume are inversely proportional.
What effect does compressing a gas at constant temperature have on its volume and pressure?
It decreases the volume, which increases the pressure.
True or False?
Expanding a gas at constant temperature decreases its pressure.
True.
Increasing the volume of a gas decreases its pressure, provided the temperature stays constant.
Why does compressing a gas increase its pressure, in terms of molecular collisions?
The molecules hit the walls of the container more frequently, creating a larger net force on the walls.
The pressure of a gas produces a net force at ______ to the wall of its container.
The pressure of a gas produces a net force at right angles to the wall of its container.
What do p and V represent in the equation pV = constant, and what are their units?
p = pressure, in pascals (Pa). V = volume, in metres cubed (m³).
What two conditions must stay constant for pV = constant (Boyle's Law) to apply to a gas?
The temperature must stay constant, and the mass (and number) of particles must stay constant.
Write the equation that relates the initial and final pressure and volume of a fixed mass of gas at constant temperature.
p1V1 = p2V2
Define work, in physics.
The transfer of energy by a force.
What effect does compressing a gas have on its internal energy and temperature?
It increases the internal energy of the gas, which can also increase its temperature.
Why does compressing a gas increase its temperature, in terms of the motion of its molecules?
A force pushes a piston, decreasing the volume, so the molecules move around faster. This increases their kinetic energy, which increases the temperature.
If a gas is allowed to ______, the gas will do work instead, causing it to lose energy.
If a gas is allowed to expand, the gas will do work instead, causing it to lose energy.
True or False?
When a gas expands and does work, its temperature increases.
False.
When a gas expands and does work, it loses energy, so its temperature decreases.
Explain why a bicycle pump feels warm when it is compressed quickly several times.
Work is done on the gas inside the pump, causing its temperature to rise.
Why does the gas and fuel mixture in a diesel engine ignite?
It is compressed very suddenly, which causes the gas to heat up and ignite the fuel.
Why can dry ice form when pressurised carbon dioxide is released from a high-pressure cylinder?
The gas does work as it expands, so it loses energy. This can cause the carbon dioxide to freeze, forming dry ice.
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