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Temperature and Heat Discussion

Physics - Fluids

Description
Read through chapter 11. These points will count toward your homework grade.

1. Question Details Notes Question: CJ7 11.CQ.004.
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As you climb a mountain, your ears "pop" because of the changes in atmospheric pressure.
(a) In which direction does your eardrum move as you climb up?
inward outward eardrum does not move

Give your reasoning.

(b) In which direction does your eardrum move as you climb down?
inward outward eardrum does not move

Give your reasoning.

2. Question Details Notes Question: CJ7 11.CQ.007.
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A large closed tank is completely filled with water. A valve is then opened at the bottom of the tank and water begins to flow out. When the water stops flowing, will the tank be completely empty, or will there still be a noticeable amount of water in it?
tank will have a noticeable amount of water in it tank will be completely empty

Explain your answer.

3. Question Details Notes Question: CJ7 11.CQ.008.
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Could you use a straw to sip a drink on the moon?
yes no not enough information to decide

Justify your answer.

4. Question Details Notes Question: CJ7 11.CQ.010.
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A scuba diver is below the surface of the water when a storm approaches, dropping the air pressure above the water. Would a sufficiently sensitive pressure gauge attached to his wrist register this drop in air pressure?
yes, if the gauge was designed to measure gauge pressure yes, if the gauge was designed to measure absolute pressure yes, if the gauge was designed to measure partial pressure no, the gauge would not register this drop in air pressure

Give your reasoning.

5. Question Details Notes Question: CJ7 11.CQ.011.
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A steel beam is suspended completely under water by a cable that is attached to one end of the beam, so it hangs vertically. Another identical beam is also suspended completely under water, but by a cable that is attached to the center of the beam so it hangs horizontally. Which beam, if either, experiences the greater buoyant force? Neglect any change in water density with depth.
both beams experience the same buoyant force the vertically suspended beam the horizontally suspended beam

Provide a reason for your answer.

6. Question Details Notes Question: CJ7 11.CQ.012.
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A glass beaker, filled to the brim with water, is resting on a scale. A block is placed in the water, causing some of it to spill over. The water that spills is wiped away, and the beaker is still filled to the brim. How do the initial and final readings on the scale compare if the block is made from the following materials?
(a) wood
initial reading is greater than the final reading initial reading is lesser than the final reading initial reading is equal to the final reading

Explain your answer, using data from Table 11.1 and Archimedes' principle.

(b) iron
initial reading is greater than the final reading initial reading is lesser than the final reading initial reading is equal to the final reading

Explain your answer, using data from Table 11.1 and Archimedes' principle.

7. Question Details Notes Question: CJ7 11.CQ.013.
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On a distant planet the acceleration due to gravity is less than it is on earth. Would you float more easily in water on this planet than on earth?
yes no floating on water on the planet would be the same as that on earth

Account for your answer.

8. Question Details Notes Question: CJ7 11.CQ.014.
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Put an ice cube in a glass, and fill the glass to the brim with water. When the ice cube melts and the temperature of the water returns to its initial value, would the water level drop, remain the same, or rise (causing water to spill out)?
water leve remains the same water level rises water level drops

Explain what you would observe in terms of Archimedes' principle.

9. Question Details Notes Question: CJ7 11.CQ.015.
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As a person dives toward the bottom of a swimming pool, the pressure increases noticeably. Does the buoyant force also increase? Neglect any change in water density with depth.
yes no not enough information to decide

Justify your answer.

10. Question Details Notes Question: CJ7 11.CQ.019.
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Concept Simulation 11.1 reviews the central idea in this question. The cross-sectional area of a stream of water becomes smaller as the water falls from a faucet. Account for this phenomenon in terms of the equation of continuity.

What would you expect to happen to the cross-sectional area when the water is shot upward, as it is in a fountain?
cross-sectional area remains the same cross-sectional area becomes larger cross-sectional area becomes smaller

Explain.

11. Question Details Notes Question: CJ7 11.CQ.020.
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Have you ever had a large truck pass you from the opposite direction on a narrow two-lane road? You probably noticed that your car was pulled toward the truck as it passed. What can you conclude about the speed of the air between your car and the truck compared to that on the opposite side of the car?
the speed of the air between the car and the truck is lesser than that on the opposite side of the car the speed of the air between the car and the truck is greater than that on the opposite side of the car the speed of the air between the car and the truck is the same as that on the opposite side of the car

Provide a reason for your answer.

12. Question Details Notes Question: CJ7 11.CQ.022.
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Hold two sheets of paper by adjacent corners, so that they hang downward. They should be parallel and slightly separated, so that you can see the floor through the gap between them. Blow air strongly down through the gap. Do the sheets move further apart, or do they come closer together?
sheets move apart sheets come closer together

Discuss what you observe in terms of Bernoulli's equation.

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Solution Preview

1)
a) outward
Reason : The atmospheric pressure drops with elevation. Our body adjusts to the low pressure by blowing air out.

b) inward
Reason : The atmospheric pressure increases when going down. The higher pressure outside will push the eardrum.

2) The tank will have a noticeable amount of water in it.
Reason : vacuum is created above the water level. The mass of the column of water left in the tank is not enough to push
itself out.
3) no
Reason : The atmosphere of moon is vacuum. We displace air in the straw to pull the fluid we drink.

4) Yes, if the gauge was designed to measure absolute pressure.
Reason : Absolute pressure includes not just the water pressure but also the pressure of the air above the water surface.

5) Both beams experience the same buoyant force.
Reason : Buoyant force is dependent on the volume of water displaced by the beam. Since both beam are identical, they both displaced equal volumes of water.

6) a) The initial reading is greater than the final reading.
Reason : ...

Solution Summary

A temperature and heat discussion is provided.

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