Solids, Liquids and Gases

Question 1

Explain what is meant by density of a material

Answer 1

• It is the mass per unit volume of the material. e.g.
• It states how many kg is the mass of one meter-cube of the material
• It states how many g is the mass of one centimeter-cube of the material

Question 2

What equation is used to calculate density, when you know the mass and volume?

Answer 2

Question 3

What is pressure?

Answer 3

• It is the amount of force applied per unit area e.g. How many newtons of force applied per meter-square

Question 4

State an equation linking pressure, force and area

Answer 4

Question 5

What is the SI unit of pressure?
How else it can be expressed?

Answer 5

Question 6

In solids, pressure acts in the direction of force.
In which direction does pressure act in liquids or gases?

Answer 6

It acts in all directions equally

Question 7

State an equation linking pressure difference, depth (height), density of liquid and gravitational field strength.

Answer 7

Question 8

How do you convert between degree Celsius and Kelvin?

Answer 8

Question 9

Explain why kelvin scale is used in science instead of celsius scale.

Answer 9

Question 10

What is absolute zero?

Answer 10

Question 11

Explain the pressure of a gas in terms of the motion of particles.

Answer 11

The particles move in random directions. When they collide with the walls of a container they exert a force which acts at a right angle to the container. This causes pressure.

Question 12

How does changing the temperature of a gas affect the velocity of the particles?

Answer 12

The higher the temperature, the more kinetic energy the particles have and therefore the faster the average velocity of the particles.

Question 13

How does temperature affect the pressure of a gas?

Answer 13

Increasing temperature increases the average kinetic energy of particles so they move faster. Therefore particles collide harder and more frequently. This increases the pressure

Question 14

State an equation linking initial pressure, final pressure, initial temperature and final temperature

Answer 14

Question 15

Explain how changing the volume of a gas affects the pressure of the gas

Answer 15

Volume and pressure are inversely proportional assuming temperature and mass of the gas is kept constant. Therefore as volume decreases(gas is compressed) pressure increases; as volume increases(gas is expanded) pressure decreases

Question 16

State an equation linking initial pressure, initial volume, final pressure and final volume for a gas.

Answer 16

Question 17

State 2 assumptions you should make while using this equation

Answer 17

• Fixed mass (number of molecules)
• Fixed Temperature

Question 18

In a bicycle pump, how does pressing the piston lead to an increase in the temperature inside the piston?

Answer 18

● Pressing the piston leads to a decrease in volume
● This leads to an increase in pressure
● The particles collide more frequently
● The velocity of the particles increases
● Therefore their temperature will increase