Bernoulli's Principle

Bernoulli's principle, physical principle formulated by Daniel Bernoulli that states that

"as the speed of a moving fluid (liquid or gas) increases, the pressure within the fluid decreases."


eperiment 1


Water flows from high pressure region to low region.

Pressure at A > Pressure at B > Pressure at C.





Experiment 2

Pressure at B becomes lowest because the speed of the water is the highest.




Experiment 3

Pressure at B becomes lowest because the speed of the water is the highest

Archimedes’ Principle

Archimedes Principle states that when a body is wholly or partially immersed in a fluid it experiences an upthrust equal to the weight of the fluid displaced.



Buoyant force
Buoyant force is an upward force exerted by a fluid on an object immersed in it.

Principle of Floatation:
•Displaced volume of fluid = volume of the object that immerse in the fluid.
•If weight of the object > upthrust, the object will sink into the fluid.
•If weight of the object = upthrust, the object is in balance and therefore float on the surface of the fluid.


Density of Object < Density of water: Partially Immerse





Upthrust = Weight

Upthrust, F = ρliquidVliquidg
Weight, W = mg =ρobjectVobjectg






Density of Object < Density of water: Fully Immerse





F = T + W

F = Upthrust
T = Tension of the string
W = Weight

Upthrust, F = ρliquidVliquidg
Weight, W = mg =ρobjectVobjectg

pascal principle!

Pascal's principle states that any change in pressure applied to an enclosed liquid will be transmitted to every point of the fluid without any change in magnitude.


Pascal's Priciple - Prove





When the plunger is pushed in, the water squirts equally from all the holes. This shows that the pressure applied to the plunger has been transmitted uniformly throughout the water.



Hydraulic System










F1 = Force exerted on the small piston
A1 = area of the small piston
F2 = Force exerted on the big piston
A2 = area of the big piston

The hydraulic system acts as a force multiplier


Hydraulic Jack





-When the handle is pressed down, valve A is closed whereas valve B is opened. The hydraulic fluid is forced into the large cylinder and hence pushes the piston moving upward.

-When the handle is raised, valve B will be closed while vale A will be opened. Hydraulic fluid from the buffer tank will be suck into the small cylinder.

-This process is repeated until the load is sufficiently lifted up.

-The large piston can be lowered down by releasing the hydraulic fluid back to the buffer tank through the release vale.