Sectieoverzicht

    • What is pressure?

      Pressure influences our daily lives without us even knowing it, here are some examples:

      • Sharp knives help us cut through meat or vegetables
      • Hammers are used to insert nails into wood to build a desk or cabinet
      • Backpacks have thick padded shoulder straps to ensure that a loaded pack won't dig into your shoulders and hurt you
      • When you walk on grass in high heels do you  notice how your heels sink into the grass whereas if you wear flat heels they don't?
      • And so the list can go on...


      But what exactly is pressure?


    • Consider the following two scenarios:

      Scenario one

      If you hammer a nail into a piece of wood with the sharp point against the wood, the nail should go into the wood quite easily. However, if you flip the nail so that the head of the nail is against the wood, and then use the same amount of force and try to hammer the nail into the wood, you will not be very successful.


      Scenario two

      If you try and push two pieces of wood, using the same amount of force, into a softer object, you will observe that the piece of wood with the smaller surface area will penetrate the object easier than the wood with the larger surface area.


      So what can we conclude from these two scenarios?

      When force is applied to an object, the results are affected by the size of the surface area on which the force is applied. This is the concept of pressure. An object will experience pressure when force is applied to it. There is a direct relationship between force and the surface area on which it is applied, the smaller the surface area, the larger the amount of pressure exerted.

      \( Pressure = Force \div Area \) 

      or in another format:


    • What unit is pressure measured in?

      Now that you know the formula to measure pressure viz.:


      you need to understand the unit that pressure is measured in.

      • Force is measured in Newtons (N)
      • Area is measured in m2  or cm2
      • Therefore pressure is measured in Newton per square metre: N/m2  
      • N/m2  is also known as the Pascal Pa. 1 Pa = 1 N/m2

    • Activity

      Using the forum tool below, provide some other examples of how pressure manifests itself e.g. a high heel in grass versus a flat heel in the grass.

      Each participant should post at least one comment. Review what other course participants have posted.

    • Forum discussion
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    • Watch the short YouTube video below which clearly summarises what has been covered so far:


      NinetyEast. (2019). What is pressure? (Standard YouTube licence)