# Lesson 2 — Recap force, start pressure

Pressure
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Slide 1: Tekstslide

In deze les zitten 18 slides, met interactieve quizzen en tekstslides.

## Onderdelen in deze les

Pressure

What is force?

#### Slide 2 -Open vraag

Force
A push or pull that changes the way an objects moves.

#### Slide 3 -Tekstslide

What is the unit of force?
A
Joule (J)
B
Watt (W)
C
Newton (N)
D
Kilogram (kg)

#### Slide 4 -Quizvraag

What are the three effects that a force can have on objects?

#### Slide 5 -Open vraag

Forces can:
• Accelerate or decelerate objects.
• Change the direction of a motion.
• Change the shape of an object.

What is weight?

#### Slide 7 -Open vraag

Weight
The magnitude of the force of earths gravity acting on a specific object.
• A cat has a mass of 4 kg.
• The earth pulls on him with a force of 39.2 Newton.
• The cat has a weight of 39.2 Newton.

#### Slide 8 -Tekstslide

What is the formula for weight?
A
Weight = Force x gravitational field strength
B
W = mass x gravitational field strength
C
Weight = mass x gravitational field strength x height
D
Weight = mass x forces

#### Slide 9 -Quizvraag

Demonstration pressure

#### Slide 10 -Tekstslide

This lesson
• Recap forces
• Pressure demonstration
• The formula for pressure + exercises
• To do for the coming week — Working independently

#### Slide 11 -Tekstslide

Learning goals
• Describe what a forces is and it's three effects on motion.
• Name the unit of force.
• Name the formula for weight.
•  Name the formula for pressure and all the accompanying units.
• Apply the formula for pressure in calculations.

#### Slide 12 -Tekstslide

Pressure
ρ=AF
pressure=AreaForce
Pressure (ρ): Pascal (Pa – N/m2), N/cm2
Force (V): N
Area (m): m2, cm2

#### Slide 13 -Tekstslide

Exercise
a) Find the pressure exerted by a force of 72 Newtons on an area of 6 m2. Give your answer in N/m2.

#### Slide 14 -Tekstslide

Exercise
a) Find the pressure exerted by a force of 72 Newtons on an area of 6 m2. Give your answer in N/m2.

Lets look at the yellow block exercises

#### Slide 15 -Tekstslide

Exercise
A woman weighing 76 kg is wearing high heels to the zoo. She goes to see an elephant with a mass of 5221 kg. One of her heels has a total area of 8.4 cm2. One of the elephants feet has an area of 301 cm2.

a) Without making calculations, make an estimation of wether the elephant or the women applies a greater pressure to the ground. Write down your reasoning.

b) Calculate the pressure the women applies to the ground.

c) Calculate the pressure the elephant applies to the ground.

#### Slide 16 -Tekstslide

Next week — to do list
• 8.1
• 8.2

Do:
• 8.1 yellow block exercises
• 8.1 workbook exercises
• 8.2 yellow block exercises
• 8.2 workbook exercises

#### Slide 17 -Tekstslide

Learning goals
• Describe what a forces is and it's three effects on motion.
• Name the unit of force.
• Name the formula for weight.
•  Name the formula for pressure and all the accompanying units.
• Apply the formula for pressure in calculations.