Fluids

1. An uncooked egg sinks in fresh water but floats in salt water. Which of the following expressions about the egg’s density (ρegg) with respect to the density of freshwater (ρfw) and the density of salt water (ρsw) is correct?

• ρegg < ρfw < ρsw

• ρfw < ρegg < ρsw

• ρsw < ρegg < ρfw

• ρfw < ρsw < ρegg

A stone tied up to the spring balance then dipped in the water. After reaching a certain depth, the weight of stone decrease as shown. What is the buoyant force exerted on the stone? Assume the fluid is water ρ=1000 kg/m3

• 0.15 N  

• 0.50 N  

• 1.5 N 

• 0.65 N

Archimedes' Principle states that... 

• 1. The buoyant force acting on an object equals the volume of the fluid displaced by the object.

• 1. The buoyant force acting on an object equals the weight (force of gravity) of the fluid displaced by the object.

• 1. The buoyant force acting on an object will always be equal. 

 During a hurricane, the air outside a home moves much faster than the air inside the home. Which of the following is possible to happen?

• 1. The windows can burst inward.

• 1. The windows cannot burst because the pressure inside and outside the home are equal.

• 1. The windows can burst outward.

• The windows cannot burst because the force inside and outside the home are equal.

Water flows in a horizontal pipe that is narrow but then widens. The pressure of the water moving in the pipe is

• greater in the wide part

• 1. greater in the narrow part

• the same in both parts

• not enough information

Air rushes through a tube connected to a straw. The bottom of the straw is placed in water. Which of the following results from this scenario?

• 1. Water flows out of the straw so its water level is lower than that around it.

• The water level stays equal inside and outside the straw.

• Water flows into the straw so its water level is higher than that around it.

• Not enough information

Four straws are open to water on the bottom and are exposed to flowing air going through an irregular tube on the top. Which cylinder will have the highest water level?

• A

• B

• C

• D

• E

 Water flows through a pipe whose area is constant but whose height above the ground changes. How does speed v2 compare to v1?

• v1 is greater

• v2 is greater

• both speeds are equal

• not enough information

Point A of a tube is pressurized to 8 atm so that water flows uphill to tubes B, C, and D. At which point is the water speed the greatest?

• A

• B

• C

• D

Rank the sections in order from greatest pressure to least. (Refer to figure in #9)

• A, B, C, D

• A, B = C = D

• D, C, B, A

• B = C = D, A