What is Buoyancy and Flotation in Fluid mechanics. Relationship between Buoyancy and Flotation. Why a body sinks or floats.

1. BUOYANCY AND
FLOTATION
• NAME: MALIHA MEHR QAMBRANI
• SEMESTER: 3RD
• Instructor: Dr. Engr. Zafar Lashari
• “FLUID MECHANICS”
• DEPARTMENT OF CIVIL ENGINEERING

2. BUOYANCY FLOTATION
The force on an
object exerted by
the surrounding
fluid. When an
object pushes
water, the water
pushes back with
as much force as
it can.
If the water can
push back as
hard, the object
floats. e.g., boat.
If not, it sinks.
e.g., steel.

3. Positive buoyancy (Floating):
Buoyant force is greater than weight so the object floats.
Neutral buoyancy (Suspending):
Buoyant force is equal to weight, so the object is suspended in the fluid.
Negative buoyancy (Sinking):
Buoyant force is less than weight so the object sinks.

4. Archimedes' Principle
Buoyant Force = Weight of displaced (by object)
fluid.
Calculating BF?
BF = W(air) – W(water)
Q- Why ice floats while steel sinks in water?
Ans. 1 cm3 of steel weighs more than the 1 cm3
of water it displaces, so it sinks.
1 cm3 of ice weighs less and so it is pushed up.

6. ANY QUESTIONS?

7. THANK YOU FOR
YOUR ATTENTION!