1. Forces in Fluids: Buoyant Force

2. Forces In Fluids A force is a push or pull that acts on an object.
EXAMPLE: Weight is the amount of downward pull on a object due to gravity
Measuring the unit in force is the newton (N)

3. BUOYANCY BUOYANCY = the ability to float in a fluid.
Examples of fluids = water, air
BUOYANT FORCE = the upward force that acts on a submerged object.
It acts opposite of gravity

4. THE BIGGER FORCE WINS, SO THE BLOCK SINKS
WEIGHT OF OBJECT
THE BIGGER FORCE
WINS, SO THE BLOCK
SINKS
BUOYANT
FORCE

5. This beach ball floats.
Why?

6. Because the Buoyant Force is greater than the weight of the ball.

7. ARCHIMEDES’ PRINCIPLE
The buoyant force acting on a submerged object is equal to the weight of the fluid the object displaces.
Video

9. How Buoyancy Works Example
If you could weigh the water that the wood displaces,  you would find that its weight equals the weight of the  wood.
Thus, the wood floats.
Wood in a pail of water

10. OBJECT RISES ABOVE SO THE BEACH BALL RISES. WATER
Having a lower density than fluid means that the beach ball’s buoyant force is higher than the force of gravity on beach ball/object.
SO THE BEACH
BALL RISES.
WATER

11. OBJECT SINKS SO THE CINDER BLOCK SINKS. WATER
Having a higher density than fluid means that the cinder block’s buoyant force is lower than the force of gravity on cinder block/object
SO THE CINDER
BLOCK SINKS.
WATER

12. Object Floats SO THE BOOT NEITHER SINKS NOR RISES, it FLOATS WATER
Having the same density as water means that the boot’s buoyant force is equal to the gravity’s force on the boot/object.
SO THE BOOT
NEITHER SINKS
NOR RISES, it
FLOATS
WATER

13. Which direction does the buoyancy force act on an object? A upward
3.2 Pressure and the Buoyant Forces A B C D
Which direction does the buoyancy force act on an object?
A upward
B downward
C to the left of the object
D to the right of the object
Lesson 2 Review

14. Where is the pressure the greatest on an object in a fluid? A top
3.2 Pressure and the Buoyant Forces A B C D
Where is the pressure the greatest on an object in a fluid?
A top
B bottom
C sides
D none of the above
Lesson 2 Review