Explain what pressure is, name the formula for pressure and do calculation exercises about pressure.
Explain what weight is, name the formula for weight and do calculation exercises about weight.
Convert m2 to cm2 and the other way around.
Convert N/m2 to N/cm2 and the other way around.
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Recap
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Demonstration
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Pressure
A measure of force applied to the surface of an object
Quantity
Unit
Pressure (P)
Pascal (Pa)
Force (F)
Newton (N)
Area (A)
m2
Pressure=AreaForce
P=AF
Formula
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What is weight?
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Weight
The magnitude of the force of gravity exerted on a specific object.
Quantity
Unit
Weight
Newton (N)
Mass
kilogram (kg)
gravitational field strength
Newton / kilogram (N/kg)
Weight=mass⋅gravitationalfieldstrength
W=m⋅g
Formula
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Calculating weight
A) A man with a mass of 80 kilogram (kg) is carrying a box with a mass of 22,5 kilogram (kg). The gravitational field strength on earth is 9.8 Newton/kilogram (N/kg). Calculate the weight of this man and the box together.
B) On the moon this man's weight would be 165 Newton. calculate the gravitational field strength of the moon
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 in N/m2.
c) Calculate the pressure the elephant applies to the ground N/m2.
P=AF
W=m⋅g
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Homework
The exercise in the previous slide (uploaded on somtoday)
The workbook exercises of 8.2
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Learning goals
By the end of this lesson you will be able to:
Explain what pressure is, name the formula for pressure and do calculation exercises about pressure.
Explain what weight is, name the formula for weight and do calculation exercises about weight.