Lesson 14 2E

• Science
• Middelbare school
• havo
• Leerjaar 2

This lesson

• Recap
• Discussing the homework
• Pressure, temperature and volume
• Density

Learning goals

•  Explain what creates the pressure in a gas.
• Describe the relationship between pressure, temperature and volume in a gas.
• Explain what is meant by density.
• Name the formula for density and be able to apply it in calculations.

Two types of relationships

Directly proportional

Inversely proportional 

Directly proportional:

When one factor increases, the other one also increases

Inversely proportional:

When one factor increases, the other one decreases

Directly proportional:

• The time you exercise for and how much energy you use.
• The amount of hours you work and how much money you make.

Inversely proportional:

• The speed of a car and how long it's journey is.
  
• The amount of money you have and how much stuff you buy.
  

Pressure in gasses — Questions

1. What causes a gas to exert pressure on its surroundings?

2. Why does the pressure inside of a balloon increase when you put more air into it?

3. Describe the relationship between the pressure in a gas and the volume of the container it is in? What type of relationship is this?

4. Describe the relationship between the pressure in a gas and the temperature of the gas. What type of relationship is this?

5. What will happen to the tires of your bike on a hot summer day compared to a cold winter day? Assume the same amount of air is in them in both days.

6. What do you call the pressure the air around you exerts on your body?

7. Is the pressure at a mountain top larger or smaller than at sea level? Explain your answer.

8. Why do mountain climbers have to carry oxygen tanks with them when climbing high mountains?

pressure, temperature and volume

(in gasses)

Link

Density

A bowling ball and a football

• What do they have in common?
  
• What is different between them?
  

What is density?

Density is

• The ratio between mass and volume of an object or a substance.
  
• A property of a substnace.

Density=​volume​​mass​​

Density=​volume​​mass​​

ρ=​v​​m​​

ρ: density – g/cm3, kg/m3

m: massa – g, kg

v: volume – cm3, m3

Density exercise

Exercise 1) A rectangular block of copper has a mass of 1896 g. The dimensions of the block are 8.4 cm by 5.5 cm by 4.6 cm. From this data, what is the density of copper?

Exercise 2) A block of ice has a volume of 980 cm³. The density of ice is 0.917 g/cm³. Calculate the mass of this block of ice.

What makes objects 

float or sink?

Link

Objects float on a liquid if they are less dense then that liquid

Objects sink into a liquid if they are denser then that liquid 

Learning goals

•  Explain what creates the pressure in a gas.
• Describe the relationship between pressure, temperature and volume in a gas.
• Explain what is meant by density.
• Name the formula for density and be able to apply it in calculations.