Pressure is the force exerted per unit area , measured in pascals (Pa).

Which area should be used when calculating the pressure exerted by a force on a surface?

The cross-sectional area — the area where the force acts at right angles to the surface.

Define Brownian motion .

Brownian motion is the random motion of tiny particles in a fluid, caused by collisions with fast-moving molecules.

Explain why increasing the temperature of a gas at constant volume increases its pressure.

The molecules move at a higher speed , so they collide with the container walls more frequently and with greater force , increasing the pressure.

At constant volume, increasing the temperature of a gas ______ its pressure.

At constant volume, increasing the temperature of a gas increases its pressure.

True or False? Gas molecules travel in a fixed, repeating path between collisions.

False. Gas molecules move in random motion, with no fixed path, undergoing sudden changes in direction when they collide with the container walls or other molecules.

Define absolute zero .

Absolute zero is the temperature at which the molecules in a substance have zero kinetic energy , equal to -273 °C.

Why do gas particles exert no pressure on their container at absolute zero?

At absolute zero the particles have zero kinetic energy and are no longer moving , so they cannot collide with the container walls.

The Kelvin scale begins at absolute zero, where 0 K is equal to ______ .

The Kelvin scale begins at absolute zero, where 0 K is equal to -273 °C .

True or False? A temperature in kelvin can be a negative value.

False. Since the Kelvin scale begins at absolute zero , it is not possible to have a temperature below 0 K.

How does a change in temperature of 1 K compare to a change in temperature of 1 °C?

They are equal — an increase of 1 K is the same size change as an increase of 1 °C .

When a gas is compressed, its volume ______ and its pressure ______ .

When a gas is compressed, its volume decreases and its pressure increases .

What happens to the pressure of a gas when it expands at constant temperature? Why?

The pressure decreases , because the molecules collide with the container walls less frequently .

In which direction do gas molecules exert a net force when they collide with a container wall?

At right angles (perpendicular) to the wall.

Why does compressing a gas increase its density?

The same number of molecules now occupies a smaller volume , so the density increases.

True or False? When a gas is compressed at constant temperature, the number of gas molecules increases.

False. The number of molecules stays the same — only the volume decreases, increasing the frequency of collisions with the container walls.

What two quantities must remain constant when relating a change in a gas's volume to a change in its pressure?

The temperature and the mass (number of particles) of the gas.

What two conditions must be kept constant for Boyle's Law to apply?

The temperature and the mass (number of particles) of the gas.

According to Boyle's Law, pressure and volume are ______ proportional.

According to Boyle's Law, pressure and volume are inversely proportional.

True or False? According to Boyle's Law, doubling the volume of a fixed mass of gas at constant temperature will double its pressure.

False. Pressure and volume are inversely proportional, so doubling the volume halves the pressure.

Define work , in the context of doing work on a gas.

Work is the transfer of energy by a force . Doing work on a gas transfers energy to it, increasing its internal energy .

What happens to the temperature of a gas when work is done on it by compression? Why?

The temperature increases , because the molecules gain kinetic energy and move faster.

What happens to the temperature of a gas when it expands and does work? Why?

The temperature decreases , because the gas loses energy as it does work.

Explain why a bicycle pump feels warm when compressed rapidly several times.

Work is done on the trapped gas by compression, transferring energy to it and increasing its temperature .

Why does releasing pressurised carbon dioxide from a cylinder cause it to freeze into dry ice?

As the gas expands rapidly, it does work , losing energy, which causes a large decrease in temperature.

When a gas expands and does work, it ______ energy, causing its temperature to ______ .

When a gas expands and does work, it loses energy, causing its temperature to fall .

True or False? Compressing a mixture of fuel and air in a diesel engine causes it to heat up and ignite the fuel.

True. Sudden compression does work on the gas mixture, causing it to heat up and ignite the fuel.

GCSEPhysicsEdexcelFlashcards14. Particle ModelParticle Model & Pressure

Particle Model & Pressure (Edexcel GCSE Physics): Flashcards

Exam code: 1PH0

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Define pressure.

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Cards in this collection (32)

Define pressure.
Pressure is the force exerted per unit area, measured in pascals (Pa).
State the equation linking pressure, force and area.
$p = \frac{F}{A}$
Which area should be used when calculating the pressure exerted by a force on a surface?
The cross-sectional area — the area where the force acts at right angles to the surface.
Define Brownian motion.
Brownian motion is the random motion of tiny particles in a fluid, caused by collisions with fast-moving molecules.
Explain why increasing the temperature of a gas at constant volume increases its pressure.
The molecules move at a higher speed, so they collide with the container walls more frequently and with greater force, increasing the pressure.
At constant volume, increasing the temperature of a gas ______ its pressure.
At constant volume, increasing the temperature of a gas increases its pressure.
True or False?
Gas molecules travel in a fixed, repeating path between collisions.
False.
Gas molecules move in random motion, with no fixed path, undergoing sudden changes in direction when they collide with the container walls or other molecules.
Define absolute zero.
Absolute zero is the temperature at which the molecules in a substance have zero kinetic energy, equal to -273 °C.
Why do gas particles exert no pressure on their container at absolute zero?
At absolute zero the particles have zero kinetic energy and are no longer moving, so they cannot collide with the container walls.
State the equation used to convert a temperature T in kelvin to a temperature θ in Celsius.
$θ / ° C = T / K - 273$
The Kelvin scale begins at absolute zero, where 0 K is equal to ______.
The Kelvin scale begins at absolute zero, where 0 K is equal to -273 °C.
True or False?
A temperature in kelvin can be a negative value.
False.
Since the Kelvin scale begins at absolute zero, it is not possible to have a temperature below 0 K.
How does a change in temperature of 1 K compare to a change in temperature of 1 °C?
They are equal — an increase of 1 K is the same size change as an increase of 1 °C.
When a gas is compressed, its volume ______ and its pressure ______.
When a gas is compressed, its volume decreases and its pressure increases.
What happens to the pressure of a gas when it expands at constant temperature? Why?
The pressure decreases, because the molecules collide with the container walls less frequently.
In which direction do gas molecules exert a net force when they collide with a container wall?
At right angles (perpendicular) to the wall.
Why does compressing a gas increase its density?
The same number of molecules now occupies a smaller volume, so the density increases.
True or False?
When a gas is compressed at constant temperature, the number of gas molecules increases.
False.
The number of molecules stays the same — only the volume decreases, increasing the frequency of collisions with the container walls.
What two quantities must remain constant when relating a change in a gas's volume to a change in its pressure?
The temperature and the mass (number of particles) of the gas.
Define Boyle's Law.
Boyle's Law states that for a fixed mass of gas at constant temperature, pressure and volume are inversely proportional:
$p V = constant$
State the equation relating the initial and final pressure and volume of a fixed mass of gas at constant temperature.
$P_{1} V_{1} = P_{2} V_{2}$
What two conditions must be kept constant for Boyle's Law to apply?
The temperature and the mass (number of particles) of the gas.
According to Boyle's Law, pressure and volume are ______ proportional.
According to Boyle's Law, pressure and volume are inversely proportional.
True or False?
According to Boyle's Law, doubling the volume of a fixed mass of gas at constant temperature will double its pressure.
False.
Pressure and volume are inversely proportional, so doubling the volume halves the pressure.
A gas occupies 0.70 m³ at a pressure of 200 Pa. Using $P_{1} V_{1} = P_{2} V_{2}$ , calculate its pressure when compressed to 0.15 m³ at constant temperature.
$P_{2} = \frac{P_{1} V_{1}}{V_{2}} = \frac{200 \times 0.70}{0.15} \approx 933 P a$
Define work, in the context of doing work on a gas.
Work is the transfer of energy by a force. Doing work on a gas transfers energy to it, increasing its internal energy.
What happens to the temperature of a gas when work is done on it by compression? Why?
The temperature increases, because the molecules gain kinetic energy and move faster.
What happens to the temperature of a gas when it expands and does work? Why?
The temperature decreases, because the gas loses energy as it does work.
Explain why a bicycle pump feels warm when compressed rapidly several times.
Work is done on the trapped gas by compression, transferring energy to it and increasing its temperature.
Why does releasing pressurised carbon dioxide from a cylinder cause it to freeze into dry ice?
As the gas expands rapidly, it does work, losing energy, which causes a large decrease in temperature.
When a gas expands and does work, it ______ energy, causing its temperature to ______.
When a gas expands and does work, it loses energy, causing its temperature to fall.
True or False?
Compressing a mixture of fuel and air in a diesel engine causes it to heat up and ignite the fuel.
True.
Sudden compression does work on the gas mixture, causing it to heat up and ignite the fuel.

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