Chapter 10(Part 4)

Forces and Pressure

Quiz TimeO Why does the balloon burst on a

single nail but not on a bed of nails?

Quiz TimeO Why does the balloon burst on a

single nail but not on a bed of nails?O The force is spread over a larger

area (bed of nails) hence force acting on each unit of area (pressure) is smaller. Therefore the balloon will not burst on a bed of nails.

10.3 What is Pressure?O Pressure is the

.O Pressure depends on and

amount of force acting on a unit area

force area

Calculation of Pressure

Example 2An elephant weighs 40 000 N. The area of each of its foot is 0.1m2. What is the pressure on the ground if the elephant is standing on 2 feet?

10.3 What is Pressure?O When area of contact is reduced,

the pressure will .

O When area of contact is increased, the pressure will .

increase

decrease

Example 2O A brick weighs 30 N. It has

dimensions of 8 cm x 10 cm x 20 cm. What is the pressure exerted by the block on the ground when it is (a) laid on its largest face? (b) laid on its smallest face

Atmospheric PressureO Air exerts a pressure on our body

known as the atmospheric pressure.O This is because the air exerts a force

on us as the surrounding air have weight.