f4c3 pg 1
TRANSCRIPT
Form4Chapter3:ForcesandPressure
CYS 1
3.1 Understanding Pressure
Pressure 1. Pressure is defined as a perpendicular force acting per unit area of a surface.
2. The SI unit of pressure is Pascal (Pa). 1 Pa is equal to 1 Newton per meter square (N/m2) 3. Factors that affect the pressure acting on a surface:
a) Magnitude of the Force The larger the force, the higher the pressure
b) Contact area The larger the contact area, the lower the pressure
Examples of Application of High Pressure Examples of Application of Low Pressure
a) Sharp Knife b) Ice Skate c) Sole of shoes with spike
a) Foundation of Building b) Snow shoes c) Tyre of tractor d) Feet of Elephant
Examples: 1. The weight of a wooden block with dimensions as shown in the figure is 12N. Calculate the
maximum pressure that the block exerts on the floor.
Solution: Maximum pressure happened when the contact area is the smallest, Area= 0.2 x 0.3 = 0.06 m2
Pressure= .
= 200 Pa.
3.2 Understanding Pressure in Liquids Pressure in Liquids 1. Pressure in liquid is as a result of the weight of the liquid acting on the surface of any objects in
the liquid. 2. Pressure of a liquid is directly proportional to :
a) the depth, h b) the density of the liquid, ρ ("rho") c) the gravitational field strength, g
3. Formulae: a) Pressure caused by a liquid
b) Pressure in a liquid
Patm = Atmospheric pressure, 1.01 x 105