Ch. 10 Fluids

A steel ball sinks in water but floats in a pool of mercury. 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) cannot be determined from the information given

A) floating on the mercury

Water flows through a pipe. The diameter of the pipe at point B is larger than at point A. Where is the speed of the water greater? A) point A B) point B C) same at both A and B D) cannot be determined from the information given

A) point A

The three common phases of matter are A) solid, liquid, and gas. B) solid, liquid, and vapor. C) solid, plasma, and gas. D) condensate, plasma, and gas.

A) solid, liquid, and gas.

A 10-kg piece of aluminum sits at the bottom of a lake, right next to a 10-kg piece of lead. Which has the greater buoyant force on it? A) the aluminum B) the lead C) Both have the same buoyant force. D) cannot be determined without knowing their volumes

A) the aluminum

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) Q B) 2Q C) 4Q D) 8Q

B) 2Q

Substance A has a density of 3.0 g/cm3 and substance B has a density of 4.0 g/cm3. In order to obtain equal masses of these two substances, the ratio of the volume of A to the volume of B will be equal to A) 1:3. B) 4:3. C) 3:4. D) 1:4.

B) 4:3.

Which one of the following is associated with the law of conservation of energy in fluids? A) Archimedes' principle B) Bernoulli's principle C) Pascal's principle D) equation of continuity

B) Bernoulli's principle

A piece of iron rests on top of a piece of wood floating in a bathtub. If the iron is removed from the wood, what happens to the water level in the tub? A) It goes up. B) It goes down. C) It does not change. D) impossible to determine from the information given

B) It goes down.

As a rock sinks deeper and deeper into water of constant density, what happens to the buoyant force on it? A) It increases. B) It remains constant. C) It decreases. D) It may increase or decrease, depending on the shape of the rock.

B) It remains constant.

Which of the following is not a unit of pressure? A) atmosphere B) N/m C) Pascal D) mm of mercury

B) N/m

A sky diver falls through the air at terminal velocity. The force of air resistance on him is A) half his weight. B) equal to his weight. C) twice his weight. D) cannot be determined from the information given

B) equal to his weight.

Salt water is more dense 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 from the information given

B) less.

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) point A B) point B C) same at both A and B D) cannot be determined from the information given

B) point B

Pressure is A) proportional to both force and area. B) proportional to force and inversely proportional to area. C) inversely proportional to force and proportional to area. D) inversely proportional to both force and area.

B) proportional to force and inversely proportional to area.

Density is A) proportional to both mass and volume. B) proportional to mass and inversely proportional to volume. C) inversely proportional to mass and proportional to volume. D) inversely proportional to both mass and volume.

B) proportional to mass and inversely proportional to volume.

When you blow some air above a paper strip, the paper rises. This is 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 slower and the pressure is higher. D) the air above the paper moves slower and the pressure is lower.

B) the air above the paper moves faster and the pressure is lower.

50 cm3 of wood is floating on water, and 50 cm3 of iron is totally submerged. Which has the greater buoyant force on it? A) the wood B) the iron C) Both have the same buoyant force. D) cannot be determined without knowing their densities

B) the iron

Two Styrofoam balls, of radii R and 2R, are released simultaneously from a tall tower. Which will reach the ground first? A) Both will reach the ground simultaneously. B) the larger one C) the smaller one D) The result will depend on the atmospheric pressure.

B) the larger one

When a tube of diameter d is placed in water, the water rises to a height h. If the diameter were half as great, how high would the water rise? A) h/2 B) h C) 2h D) 4h

C) 2h

Certain insects, such as the water bug, are sufficiently lightweight that they can run on top of water without breaking the surface tension. This is possible because the water, due to surface tension, exerts an upward force on the bottom of the bug's feet. Suppose that the maximum possible upward force on the feet of water bug A is F. Now suppose that water bug B is twice as big as bug A in every dimension. That is, bug B is twice as long, twice as wide, etc. What is the maximum upward force on the feet of bug B? A) 1.4F B) 2.0F C) 4.0F D) 8.0F

C) 4.0F

Salt water has greater density than fresh water. A boat floats in both fresh water and in salt water. Where is the buoyant force greater on the boat? A) salt water B) fresh water C) Buoyant force is the same in both. D) impossible to determine from the information given

C) Buoyant force is the same in both.

A piece of wood is floating in a bathtub. A second piece of wood sits on top of the first piece, and does not touch the water. If the top piece is taken off and placed in the water, what happens to the water level in the tub? A) It goes up. B) It goes down. C) It does not change. D) cannot be determined from the information given

C) It does not change.

When atmospheric pressure changes, what happens to the absolute pressure at the bottom of a pool? A) It does not change. B) It increases by a lesser amount. C) It increases by the same amount. D) It increases by a greater amount.

C) It increases by the same amount.

As the speed of a moving fluid increases, the pressure in the fluid A) increases. B) remains constant. C) decreases. D) may increase or decrease, depending on the viscosity.

C) decreases.

What is the difference between the pressures inside and outside a tire called? A) absolute pressure B) atmospheric pressure C) gauge pressure D) N/m2

C) gauge pressure

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

D) 16Q

An ideal fluid flows at 12 m/s in a horizontal pipe. If the pipe widens to twice its original radius, what is the flow speed in the wider section? A) 12 m/s B) 6.0 m/s C) 4.0 m/s D) 3.0 m/s

D) 3.0 m/s

When a small spherical rock of radius r falls through water, it experiences a drag force arv, where "v" is its velocity and "a" is a constant proportional to the viscosity of water. From this, one can deduce that if a rock of diameter 2.0 mm falls with terminal velocity, "v", then a rock of diameter 4.0 mm will fall with terminal velocity ________. A) v B) 1.4v C) 2.0v D) 4.0v

D) 4.0v

An ideal fluid flows at 12 m/s in a horizontal pipe. If the pipe narrows to half its original radius, what is the flow speed in the narrower section? A) 12 m/s B) 24 m/s C) 36 m/s D) 48 m/s

D) 48 m/s

Certain insects, such as the water bug, are sufficiently lightweight that they can run on top of water without breaking the surface tension. Water bug A has weight W. Water bug B is twice as big as bug A, in all dimensions. That is, bug B is twice as long, twice as wide, etc. What is the weight of bug B? A) 1.3W B) 2.0W C) 4.0W D) 8.0W

D) 8.0W

Consider three drinking glasses. All three have the same area base, and all three are filled to the same depth with water. Glass A is cylindrical. Glass B is wider at the top than at the bottom, and so holds more water than A. Glass C is narrower at the top than at the bottom, and so holds less water than A. Which glass has the greatest liquid pressure at the bottom? A) Glass A B) Glass B C) Glass C D) All three have equal pressure.

D) All three have equal pressure.

You are originally 1.0 m beneath the surface of a pool. If you dive to 2.0 m beneath the surface, what happens to the absolute pressure on you? A) It quadruples. B) It more than doubles. C) It doubles. D) It less than doubles.

D) It less than doubles.

When soup gets cold, it often tastes greasy. This "greasy" taste seems to be associated with oil spreading out all over the surface of the soup, instead of staying in little globules. To us "physikers", this is readily explained in terms of A) the Bernoulli effect. B) Archimedes Principle. C) the decrease in the surface tension of water with increasing temperature. D) the increase in the surface tension of water with increasing temperature.

D) the increase in the surface tension of water with increasing temperature.

Which has the greatest effect on the flow of fluid through a narrow pipe? That is, if you made a 10% change in each of the quantities below, which would cause the greatest change in the flow rate? A) the fluid viscosity B) the pressure difference C) the length of the pipe D) the radius of the pipe

D) the radius of the pipe