1. Chapter 9 Pretest Fluids

2. 1. Because a buoyant force acts in the opposite direction of gravity, A) objects submerged in water have a net force smaller than their weight. B) objects submerged in water have a net force larger than their weight. C) objects submerged in water have a net force equal than their weight. D) objects submerged in water appear to weigh more than they do in air.

3. 1. Because a buoyant force acts in the opposite direction of gravity, A) objects submerged in water have a net force smaller than their weight. B) objects submerged in water have a net force larger than their weight. C) objects submerged in water have a net force equal than their weight. D) objects submerged in water appear to weigh more than they do in air.

4. 2. The flow rate of blood through the average human aorta is about 9
2. The flow rate of blood through the average human aorta is about 9.0 X 101 cm3/s. If the aorta has a radius of 1.0 cm, what is the velocity of the blood flow? A) 14 cm/s, B) 32 cm/s, C) 37 cm/s, D) 29 cm/s

5. 2. The flow rate of blood through the average human aorta is about 9
2. The flow rate of blood through the average human aorta is about 9.0 X 101 cm3/s. If the aorta has a radius of 1.0 cm, what is the velocity of the blood flow? A) 14 cm/s, B) 32 cm/s, C) 37 cm/s, D) 29 cm/s

6. 3. Two paper cups are hung by strings 10 cm apart
3. Two paper cups are hung by strings 10 cm apart. If a person blows between the cups, A) they move toward each other, B) they move away from each other, C) they do not move, D) they move upward.

7. 3. Two paper cups are hung by strings 10 cm apart
3. Two paper cups are hung by strings 10 cm apart. If a person blows between the cups, A) they move toward each other, B) they move away from each other, C) they do not move, D) they move upward.

8. 4. At a constant volume, an ideal gas is heated from 348 K to 423 K
4. At a constant volume, an ideal gas is heated from 348 K to 423 K. If the original pressure in the tank was 1.51 x 105 Pa and the volume does not change, what is the new pressure? A) 1.24 x 105 Pa B) 9.75 x 104 Pa C) 1.84 x 105 Pa D) 4.97 x 102 Pa

9. 4. At a constant volume, an ideal gas is heated from 348 K to 423 K
4. At a constant volume, an ideal gas is heated from 348 K to 423 K. If the original pressure in the tank was 1.51 x 105 Pa and the volume does not change, what is the new pressure? A) 1.24 x 105 Pa B) 9.75 x 104 Pa C) 1.84 x 105 Pa D) 4.97 x 102 Pa

10. 1. What is the difference in a fluid and a liquid?

11. A fluid is liquids and gases. Particles can flow around each other.

12. 2. What determines whether an object will sink or float?

13. If the density is lower than the fluid’s density
If the density is lower than the fluid’s density. If the buoyant force is equal to the weight.

14. 3. What is the pressure at a depth of 650 m in a lake?

15. P2 = P1 + rgh P2 = (10)650 P2 = Pa

16. 4. (A) Water flows through a hose with a diameter of 0
4. (A) Water flows through a hose with a diameter of 0.20 cm at a speed of 3.0 m/s. If you put your thumb over the end of the hose and produce an effective diameter of cm, at what speed does the water exit the hose? (B) If the pressure at the faucet is 3 x 105 Pa, what is the pressure at the thumb-covered end of the hose?

17. Av = Av p(0. 12) x 3 = p(0. 052) x v v = 12 m/s P1 + 1/2 ρv12 + ρgh1 =
Av = Av p(0.12) x 3 = p(0.052) x v v = 12 m/s P1 + 1/2 ρv12 + ρgh1 = P2 + 1/2 ρv22 + ρgh2 3 x /2 (1000)32 = P2 + 1/2 (1000)122 P2 = Pa

18. 5. My mass is 80 kg. If the total surface area of my feet is 0
5. My mass is 80 kg. If the total surface area of my feet is 0.08 m2, what is the pressure exerted by my feet on the floor? If I lift one foot, how does my weight change? If I lift one foot how does the pressure change?

19. P = F/A P = 80 x 10 / Pa No change in weight, but the pressure is doubled (half the area).