• Pressure?is defined as

The concentration?of a force or the force per unit area

• For example, when a drawing pin is pushed downwards:
  • It is pushed into the surface, rather than up towards the finger
  • This is because the sharp point is more?concentrated?(a small area) creating a?larger?pressure

   

When you push a drawing pin, it goes into the surface (rather than your finger)

• Example 1:?Tractors
  • Tractors have?large tyres
  • This spreads the weight (force) of the tractor over a large area
  • This reduces the pressure which prevents the heavy tractor from sinking into the mud

   

• Example 2:?Nails
  • Nails have?sharp pointed ends?with a very small area
  • This concentrates the force, creating a large pressure over a small area
  • This allows the nail to be hammered into a wall

   

• The pressure at the surface of a fluid can be calculated using the equation:

• Pressure is measured in the units?Pascals (Pa)
• The area should always be the?cross-sectional area?of the object
  • This means the area where the force is at right angles to it

   

• This equation can be rearranged with the help of a formula triangle:

Pressure, force, area formula triangle

• This equation tells us that:
  • If a force is spread over a?large?area it will result in a?small?pressure
  • If it is spread over a?small?area it will result in a?large?pressure

   

High heels produce a higher pressure on the ground because of their smaller area, compared to flat shoes

Step 1: List the known quantities

• • Cross-sectional area = 2.73 × 10^-2?m²
  • Pressure = 5.28 × 10⁵?Pa

   

Step 2: Write down the relevant equation

Step 3: Rearrange for the force,?F

F?=?p?×?A

Step 4: Substitute the values into the equation

F?= (5.28 × 10⁵) × (2.73 × 10^-2) = 14 414.4

Step 5: Round to the appropriate number of significant figures and quote the correct unit

F?= 14 400 N =?14.4 kN?(3 s.f)