1. FLUID PHYSICS

2. Lab: Buoyancy Challenge

3. Lab: Buoyancy Challenge
Data Chart

4. Upward Force Produced on an Object by a Surrounding Fluid
Buoyancy
Upward Force Produced on an Object by a Surrounding Fluid

5. Fb = Weight of Displaced Water
Buoyancy
Fb = Weight of Displaced Water

6. Fb = Real Weight – Apparent Weight
Buoyancy
Fb = Real Weight – Apparent Weight

7. Decrease an object’s density, it floats!
Buoyancy Factors
Decrease an object’s density, it floats!

8. Increase an object’s density, it sinks!
Buoyancy Factors
Increase an object’s density, it sinks!

9. Buoyancy Factors
Fluid’s Density

10. F(b) = Force of Buoyancy F (b) = Object’s Weight – Apparent Weight
Buoyancy Formulas
F(g) = Object’s Weight
F(b) = Force of Buoyancy
ρ(o) = Object’s Density
ρ(f) = Fluid’s Density
F (b) = Object’s Weight – Apparent Weight
F(g) ρ(o)
F(b) ρ(f)

11. Sample Problem
King Hiero sent his gold crown out to be fixed. The king heard that his crown had been altered and no longer was pure gold. The king measured the crown’s weight to be 7.84 N. When he immersed it in water, his scale read 6.86 N. Was his crown tampered with?

12. Calculate the force of buoyancy.
Sample Problem
Calculate the force of buoyancy.
Step 1
F(b) = F(g) – Apparent Weight
Step 2
F(b) = 7.84N – 6.86N
Step 3
F(b) = 0.98N

13. Calculate the crown’s density.
Sample Problem
Calculate the crown’s density.
Step 1
ρ(o) = F(g) · ρ(f) / F(b)
Step 2
ρ(o) = (7.84N) (1000 kg/m^3) / .98N
Step 3
ρ(o) = 8000 kg/m^3

14. Lab: Buoyant Force in Liquids
Interactive

15. Lab: Buoyant Force in Liquids
Data Chart 1
Trial #
ρ(o)
(g/cm^3)
F(b)
(N)
F(g)
F(m) 1 2 3 4

16. Lab: Buoyant Force in Liquids
Data Chart 2
Trial #
ρ(l)
(g/cm^3)
F(b)
(N)
F(g)
F(m) 1 2 3

17. Lab: Buoyant Force in Liquids
Calculation Table
Trial #
F(g) / F(b)
ρ(o) /ρ(l) 1 2 3

18. Lab: Archimedes’ Challenge

19. Lab: Archimedes’ Challenge
Data Chart
Metal
Sample
F(g)
(N)
F(apparent)
F(b) 1 2 3 4

20. Lab: Archimedes’ Challenge
Calculation Table
Metal
Sample
ρ(o)
(kg/m^3)
Identity 1 2 3 4

21. Air Pressure Demonstration

22. Pressure
Definition
Force / Unit Area

23. Pressure
Force / Unit Area

24. Pressure Formula P = F/a Units of Measurement
N/m^2 (Newtons per meters squared)
Pa (Pascals)
Atmospheres
kg/ms^2 (kilograms per meter seconds squared)

25. Sample Problem
Determine the area that a force of 2.1 N would act on to produce a pressure of 300,000 N/m^2.
Step 1
P = F/a
Step 2
300,000 N/m^2 = 2.1N / a
Step 3
a = m^2

26. Lab: Delude’s Hummer

27. Lab: Delude’s Hummer
Data Chart 1

28. Lab: Delude’s Hummer Data Chart 2 Sample Tire Length (in) Width
Left Front
Right Front
Left Rear
Right Rear

29. Lab: Delude’s Hummer Calculation Table Sample Tire Area
(square inches)
Force
(lbs)
Left Front
Right Front
Left Rear
Right Rear

30. Pressure applied to a fluid in a closed container is equally transmitted to every point of the fluid and the walls of the container.

31. Hydraulic System

32. You can lift heavy loads with minimal force.
Hydraulic System
You can lift heavy loads with minimal force.

33. The fluid pressure here… equals the fluid pressure here.
P1 = P2
F1/A1 = F2/A2

34. Sample Problem
What force is needed to raise a 14,500 N car if the radius is the large piston is 17.0 cm and the radius of the small piston is 4.0 cm?
Step 1
F1/A1 = F2/A2
Step 2
F1 /50.24 = 14,500N/907.46
Step 3
F1 = 800N

35. Static Fluid Pressure = Fluid Density • g • Height
P = ρ • g • h

36. Sample Problem 1
The Empire State Building is 366 meters high. How much pressure will you need to pump fresh water to King Kong on the top of the building?

37. Sample Problem 1
The Empire State Building is 366 meters high. How much pressure will you need to pump fresh water to King Kong on the top of the building?
Step 1
P = ρgh
Step 2
P = (1.00 x 10^3)(9.81)(366)
P = 3.59 x 10^6 Pa
Step 3

38. Sample Problem 2
The Hoover Dam is 221 meters tall. What is the pressure at the base of the dam?

39. Sample Problem 2
The Hoover Dam is 221 meters tall. What is the pressure at the base of the dam?
Step 1
P(total) = P(atmosphere) + ρgh
Step 2
P(total) = 1.01 x 10^5 +(1.00 x 10^3)(9.81)(221)
Step 3
P(total) = 2.27 x 10^6 Pa

40. What goes in a pipe must come out of the pipe!
Continuity Equation
What goes in a pipe must come out of the pipe!

41. Continuity Equation Flow Rate = Fluid Velocity x Area
Flow Rate is constant throughout the pipe.
Wide Area • Velocity = Narrow Area • Velocity

42. Step 1: Determine each pipe’s area
Sample Problem
Water flows through a horizontal pipe at a velocity of 1 m/s. If the pipe narrows to ¼ its original diameter, what will be the water’s velocity?
Step 1: Determine each pipe’s area
Pipe 2: a = πr^2
Pipe 1: a = πr^2
Pipe 2: a = π(1)^2
Pipe 1: a = π(4)^2
Pipe 1: a = 16π
Pipe 2: a = 1π

43. Step 2: Set up Continuity Equation
Sample Problem
Water flows through a horizontal pipe at a velocity of 1 m/s. If the pipe narrows to ¼ its original diameter, what will be the water’s velocity?
Step 2: Set up Continuity Equation
A1v1 = A2v2

44. Step 3: Substitute Values & Solve
Sample Problem
Water flows through a horizontal pipe at a velocity of 1 m/s. If the pipe narrows to ¼ its original diameter, what will be the water’s velocity?
Step 3: Substitute Values & Solve
(16π)(1m/s) = (1π)v2
v2 = 16m/s