1. Review of Fluid Properties
Density, Pressure, & Buoyancy

2. What is the density of water?
Ans.
1000 kg/m3 or
1 gram/cm3 or 1 gram/ml

3. George the whale displaces 32 m3 of water when floating at rest underwater. What is the George’s weight?
Ans. 320,000 N

4. The “tip of the iceberg” that is above the water represents what % of the total iceberg?
Ans. 10%

5. A cube has a density of 500 kg/m3
A cube has a density of 500 kg/m3. Will it float or sink when placed in water?
Ans. float

6. A “koosh” displaces 5 grams of water when submerged
A “koosh” displaces 5 grams of water when submerged. What is the volume of the koosh?
Ans. 5 cm3

7. What is the volume of the cube shown below?
Ans m3

8. If the cube shown below is divided into 8 pieces of equal volume, what is the mass of one of the smaller cubes?
32 kg
Ans. 4 kg

9. A cube of density 2000 kg/m3 is divided into eight identical smaller cubes. What is the density of one of the smaller cubes?
Ans kg/m3

10. A cube with a density of 4000 kg/m3 is shown below
A cube with a density of 4000 kg/m3 is shown below. What is the mass of this cube?
Ans kg
0.4 m

11. A cube with a density of 4000 kg/m3 is placed into water
A cube with a density of 4000 kg/m3 is placed into water. Once the cube is submerged, what will be the buoyant force acting on it?
Ans N
0.4 m

12. A cube with a density of 200 kg/m3 is placed in water. Will it float
A cube with a density of 200 kg/m3 is placed in water. Will it float? What will be the buoyant force acting on it?
Ans. Yes; cannot determine

13. What is the density of the cube that is floating in water as shown below?
1/3
2/3
Ans kg/m3

14. What is the weight of the 55 kg man?
Ans N

15. If the total bottom area of the 55 kg man’s feet is 0
If the total bottom area of the 55 kg man’s feet is 0.03 m2, what is the pressure at the floor when he stands on both feet?
Ans. 18,333 Pa

16. What is the pressure at the floor when the man from the previous slide stands on one foot?
Ans. 36,667 Pa

17. What is the pressure at a depth of 5 m below the surface of a lake?
Ans. 50,000 Pa

18. A treasure chest with a top area of 0
A treasure chest with a top area of 0.5 m2 sits 20 m below the surface of the sea. What is the force acting on the top?
Ans. 100,000 N

19. What is the volume of water displaced by the submerged portion of the cube?
Ans m3
Water level
0.1 m
0.04 m

20. What is the weight of the water displaced by the submerged portion of the cube?
Water level
0.1 m
0.04 m
Ans. 4 N

21. What is the weight of the cube?
Ans. 4 N
Water level
0.1 m
0.04 m

22. What is the density of the cube?
Water level
0.1 m
0.04 m
Ans kg/m3

23. A hovercraft floats on a cushion of air
A hovercraft floats on a cushion of air. If the hovercraft weighs 300,000 N, and has a base area of 340 m2, what is the pressure at the base?
Ans Pa

24. An object that weighs 5 N in air appears to weigh only 3 N when lowered into water. What is the buoyant force acting on the object?
Ans. 2 N

25. An object that weighs 5 N in air appears to weigh only 3 N when lowered into water. What is the volume of water it displaces?
Ans cm3 ( kg/m3)

26. A 5000 N car is lifted on a hydraulic piston of area 2000 cm2
A 5000 N car is lifted on a hydraulic piston of area 2000 cm2. What force is needed on the connecting 20 cm2 piston to do this?
Ans. 50 N

27. The 3000 N elephant on a 5 m2 piston platform is lifted by a 0
The 3000 N elephant on a 5 m2 piston platform is lifted by a 0.5 N mouse sitting on a ______ piston plunger.
Ans x 10-4 m2

28. Ans. A
An airship is filled with helium gas and two inflatable “ballast” bags of air. Which case below shows the flow of air when the airship rises? A B

29. Ans. high
For the fire extinguisher to work, the plunger breaks into the cylinder at point A. Is the gas in the small internal cylinder at high or low pressure? A
water