Pressure - from Paper 1 and Paper 2

Question 1

Describe the motion of gas particles

Answer 1

constant random motion

Question 2

As a gas is heated how does the particle motion change?

Answer 2

Particles move faster as they have more kinetic energy

Question 3

What causes gas pressure

Answer 3

Moving gas particles colliding with a container/object. This pressure will always create a force at a right angle to the container.

Question 4

Explain the relationship between the temperature of a gas and its pressure?

Answer 4

As temperature increase the pressure increases. This is because the particles have more kinetic energy and move faster. This means there are more collisions each second

Question 5

State the units of pressure

Answer 5

Pascals (Pa)

Question 6

If the volume of a container increases what effect will this have on pressure?

Answer 6

As volume increase pressure decreases. It is an inversely proportional relationship. A large volume will mean less collisions per second

Question 7

When work is done on a gas trying to compress it how does this affect the temperature and internal energy

Answer 7

Internal energy increases as temperature increases and particles move faster

Question 8

What is the average kinetic energy of the molecules related to?

Answer 8

The temperature of a gas

Question 9

What happens to kinetic energy if the temperature of a substance is increased?

Answer 9

The total kinetic energy of the particles increases and so the internal energy increased

Question 10

What is Boyle’s Law?

Answer 10

PV = constant (pressure and volume are inversely proportional to each other)

Question 11

State the equation for pressure with all units

Answer 11

pressure = force / area Pressure - [Pa]Force - [N]Area - [m^2]

Question 12

What is the relationship between pressure from a liquid and depth

Answer 12

As depth increases pressure increase due to a greater number of particles and force pushing on the object.

Question 13

How does liquid pressure cause upthrust?

Answer 13

A partially (or totally) submerged object experiences a greater pressure on the bottom surface than on the top surface, (pressure increases with depth). This creates a resultant force upwards. This force is called the upthrust.

Question 14

Define the atmosphere

Answer 14

The atmosphere is a thin layer (relative to the size of the Earth) of air round the Earth.

Question 15

State the relationship between altitude and the density of the atmosphere

Answer 15

The atmosphere gets less dense with increasing altitude.

Question 16

As altitude increase why does atmospheric pressure decrease?

Answer 16

Air molecules colliding with a surface create atmospheric pressure.The number of air molecules (and so the weight of air) above a surface decreases as the height of the surface above ground level increases. So as height increases there is always less air above a surface than there is at a lower height. So atmospheric pressure decreases with an increase in height.