1. PRESSURE Definition  The action of a force against some obstacle or opposing force; distributed over a surface, often estimated with reference to a unit's area.  The force exerted over a unit areaforcearea P = F/A where F – Force ( N ) A – Area ( m 2 ) Unit: N/m 2 or pascal ( pa )

2. In which instance do you feel more pressure?  Wearing flat shoes vs Wearing high-heeled shoes

3.  Standing Position vs Lying down Where do you exert more pressure?

4.  Pushing a steel cabinet vs plastic cabinet Which is easier to push?

5. Who will exert more pressure on the sofa bed?

6. What are the factors affecting the amount of pressure?  Area in contact with surface  Weight of the body or Force Pressure is inversely proportional to Area Pressure is directly proportional to Force

7. PROBLEM 1 A rectangular cabinet weighs 400N. It is 2 meters long, 1.5 meters wide and 0.5 meter thick. Find Pressure if a) the cabinet is lying on its base b) the cabinet is lying on its long side c) the cabinet is lying on its short side. In which side exerts the greatest pressure? Why?

8. Problem 2 A man exerts a force equal to his weight on the ground where he stands on. If his weight is 500N & the area of his shoes is0 0.01 m 2 then the pressure he exerts on the ground will be? If the man lies flat on the ground and area covered by his body is 0.2 m 2 then find the pressure. In which case will pressure be greater? Why?

9. Problem 3 An oxygen tank’s base is 20cm in radius, If the pressure exerted on its base is 50 pa then what is the weight of the oxygen tank? Given? Unknown?

10. Hydrostatic Pressure  this refers to the pressure exerted by the liquid. PRESSURE IN LIQUIDS Factors to consider!  Density  Height or depth

11. A man dove 35 meters under the sea. If the seawater has a density of 1030 kg/m3. Find the pressure that acts on the man’s body? Suppose the man dove on a river, how much pressure will be exerted on his body? Pressure and Density Given? Unknown?

12. P = D x h x g Where is it easier to swim in deep waters or in shallow waters? Why?  Pressure is directly proportional to Density  Pressure is inversely proportional to Height Where is it easier to swim, in the sea or in the river? Why?