Pressure
Wednesday, October 18, 2023
2:02 PM
LO: to describe how pressure changes when mass, surface area and
depth changes
1. Pressure in solids
P = F/A = mg/A
2. Pressure in fluids(liquid and gas)
P = h(rho(density))
Unit: N/m^2 or Pascal, Pa (e.g. 55N/m^2 = 55Pa)
Task 1 Calculate the pressure exerted on the table by the wooden cube:
Surface Area: 5cm * 5cm = 25cm^2 = 0.0025m^2
Weight(Mass): 27.7g = 0.277N
Pressure = mass/surface area = 0.277N/0.0025m^2 = 110.8 Pa
Task 2 Dip a mass in water and see its effect on force meter reading
Normal(F(sub1)): 75N
In Water(F(sub2)): 65N
Conclusion:
- F(sub1) is more than F(sub2) because of the force called
upthrust(buoyancy) due to water.
- Upthrust is caused by the difference between pressure at the top
and bottom of the mass
Class Notes Page 1