FLUID MECHANICS EXAM- NO NOTES

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19) Salt water is denser than fresh water. A ship floats in both fresh water and salt water. Compared to the fresh water, the volume of water displaced in the salt water is A) more. B) less. C) the same. D) Cannot be determined because we do not know the volume of the ship. Answer: B Var: 1 20) A steel ball sinks in water but floats in a pool of mercury, which is much denser than water. Where is the buoyant force on the ball greater? A) floating on the mercury B) submerged in the water C) It is the same in both cases. D) It cannot be determined from the information given. Answer: A Var: 1 21) A 10-kg piece of aluminum sits at the bottom of a lake, right next to a 10-kg piece of lead, which is much denser than aluminum. Which one has the greater buoyant force on it? A) the aluminum B) the lead C) Both have the same buoyant force. D) It cannot be determined without knowing their volumes. Answer: A Var: 1

27) When you blow some air above a paper strip, the paper rises. This happens because A) the air above the paper moves faster and the pressure is higher. B) the air above the paper moves faster and the pressure is lower. C) the air above the paper moves faster and the pressure remains constant. D) the air above the paper moves slower and the pressure is higher. E) the air above the paper moves slower and the pressure is lower. Answer: B

28) Water flows through a pipe. The diameter of the pipe at point B is larger than at point A. Where is the water pressure greatest? A) at point A B) at point B C) It is the same at both A and B. Answer: B Var: 1 29) Two horizontal pipes are the same length, but pipe B has twice the diameter of pipe A. Water undergoes viscous flow in both pipes, subject to the same pressure difference across the lengths of the pipes. If the flow rate in pipe A is Q = , what is the flow rate in pipe B? A) 2Q B) 4Q C) 8Q D) 16Q E) Q Answer: D Var: 1 30) Two horizontal pipes have the same diameter, but pipe B is twice as long as pipe A. Water undergoes viscous flow in both pipes, subject to the same pressure difference across the lengths of the pipes. If the flow rate in pipe B is Q = what is the flow rate in pipe A? A) 2Q B) 4Q C) 8Q D) 16Q E) Q Answer: A Var:

9) The weight of a 1200-kg car is supported equally by the four tires, which are inflated to the same gauge pressure. What gauge pressure is required so the area of contact of each tire with the road is 100 cm2? A) 12 × 105 Pa B) 12 × 104 Pa C) 2.9 × 105 Pa D) 2.9 × 104 Pa Answer: C

15) The Aswan High Dam on the Nile River in Egypt is 111 m high. What is the gauge pressure in the water at the foot of the dam? The density of water is 1000 kg/m3. A) 1.09 × 106 Pa B) 1.16 × 106 Pa C) 1.09 × 103 Pa D) 1.11 × 105 Pa E) 1.11 × 102 Pa Answer: A Var: 1 16) The deepest point of the Pacific Ocean is 11,033 m, in the Mariana Trench. What is the gauge pressure in the water at that point? The density of seawater is 1025 kg/m3.

A) 5.55 × 107 Pa B) 8.88 × 107 Pa C) 1.11 × 108 Pa D) 2.22 × 108 Pa E) 3.33 × 108 Pa Answer: C