Pressure

• Natuurkunde
• Middelbare school
• havo, vwo
• Leerjaar 2,3

Pressure

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You can convert metric units for distance, area and volume

You can use the formula for pressure in different situations

Pressure

To sit on a nail is painful...

for obvious reasons.

But when you sit down on 1000 nails,

you hardly feel anything anymore.

This is because the gravitational force is

equally shared over a large surface.

Pressure

Pressure=​on a surface​​Force​​

P=​A​​F​​

​(m​2​​)​​​​​(N)​​

Calculation skills

Watch these videos if you are having trouble with

• converting units
  
  
• cinvert areas and volumes
  
  
• forgot how to use formula's

Pressure example

When you dive a force of a larger surface, it will hurt less because of a smaller pressure. 

In this example you can put a block on side A or B. The surface for side B is 4 times as big as the surface of side A. This means that the experienced pressure for side B will be 4 times less as well.

It helps when you make a little drawing when you need to convert areas from cm2 to m2. It will give you a quick insight by how much you need to multiply or devide to convert the unit.

Falling through ice

This often ends fatal..

But there is something you can do.

This video is no longer available

Welke video was dit?

Therefore prepare and spread your weight as much as possible when moving over the ice.

Example question

Shufling over the ice on your stomach will make a big difference as you will found with this example.

In this question the trick is not to forget that you have two feet instead of one.

5 Steps

GIVEN

ASKED

FORMULA

CONVERT UNITS

CHECK 1 UNKNOWN & CALCULATE

Pressure in a liquid

The pressure in a liquid is equal everywhere.

Because of the constant relationship between force and surface in the equation, the pressure of the liquid will cause a bigger force near the larger cilinder (B).

Although there is more force on cilinder B, it will travel more slowly

Assignment: Thumbtack

A force of F = 1,5 N is exerted on the topside of a thumbtack.

The topsurface is A = 0,65 cm2

The surface of the needle is A = 2,1 mm2

To push the thumbtack into a bulletin board you need a pressure of 106 Pascal

a) Calculate if you can push the thumbtack into the board.

b) Calculate the minimal force needed for this

The thumbtack

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