Unit 5 Concepts Quiz
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While swimming near the bottom of a pool, you let out a small bubble of air. As the bubble rises toward the surface, what happens to its diameter?
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Bubble diameter decreases
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Bubble diameter stays the same
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Bubble diameter increases
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Explore key physics concepts with the Unit 5 Concepts Quiz. This quiz assesses understanding of fluid dynamics, buoyancy, pressure, and density through practical scenarios, enhancing comprehension of how physical principles apply to everyday phenomena.
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- 2.
Imagine holding two identical bricks in place under water. Brick 1 is just beneath the surface of the water, while brick 2 is held about 2 feet down. The force needed to hold brick 2 in place is:
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Greater
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The same
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Smaller
Correct Answer
A. GreaterExplanation
The force needed to hold the brick in place underwater is: W – FB. According to Archimedes’ Principle, FB is equal to the weight of the fluid displaced. Since each brick displaces the same amount of fluid, then FB is the same in both cases.Rate this question:
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- 3.
An object floats in water with 3/4 of its volume submerged. What is the ratio of the density of the object to that of water?
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1/4
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3/4
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4/3
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1/2
Correct Answer
A. 3/4Explanation
When an object floats in water, it displaces a volume of water equal to its own volume. In this case, since 3/4 of the object's volume is submerged, it displaces 3/4 of its own volume in water. This means that the density of the object is 3/4 times the density of water. Therefore, the ratio of the density of the object to that of water is 3/4.Rate this question:
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- 4.
Water flows through a 1-cm diameter pipe connected to a 1/2-cm diameter pipe. Compared to the speed of the water in the 1-cm pipe, the speed in the 1/2-cm pipe is:
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one quarter
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One half
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The same
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Double
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Four times
Correct Answer
A. Four timesExplanation
The area of the small pipe is less, so we know that the water will flow faster there. Since A ∝ r2, when the radius is reduced by 1/2, the area is reduced by 1/4, so the speed must increase by 4 times to keep the flow rate (A × v) constant.Rate this question:
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- 5.
A person’s blood pressure is generally measured on the arm, at approximately the same level as the heart. How would the results differ if the measurement were made on the person’s leg instead?
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The blood pressure would be lower
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The blood pressure would be higher
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The blood pressure would stay the same
Correct Answer
A. The blood pressure would be higherExplanation
Assuming that the flow speed of the blood does not change, then Bernoulli’s equation indicates that at a lower height, the pressure will be greater.Rate this question:
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- 6.
Density is...
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Proportional to both mass and volume
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Proportional to mass and inversely proportional to volume.
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Inversely proportional to mass and proportional to volume
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Inversely proportional to both mass and volume
Correct Answer
A. Proportional to mass and inversely proportional to volume.Explanation
The density of a substance is defined as its mass per unit volume. This means that as the mass of an object increases, its density also increases. On the other hand, as the volume of an object increases, its density decreases. Therefore, density is proportional to mass and inversely proportional to volume.Rate this question:
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- 7.
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
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1:3
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4:3
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3:4
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1:4
Correct Answer
A. 4:3Explanation
The ratio of the volume of substance A to the volume of substance B will be 4:3. This is because density is defined as mass divided by volume, and since we want to obtain equal masses of the two substances, we need to have the same ratio of volumes. Since substance A has a lower density than substance B, it will have a larger volume for the same mass. Therefore, the ratio of the volume of substance A to the volume of substance B will be 4:3.Rate this question:
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- 8.
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?
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Glass A
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Glass B
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Glass C
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All Equal
Correct Answer
A. All EqualExplanation
The liquid pressure at the bottom of each glass is determined by the weight of the water above it. Since all three glasses are filled to the same depth with water, they all have the same amount of water above the bottom. Therefore, the liquid pressure at the bottom of each glass is equal.Rate this question:
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- 9.
50 cm3 of wood is floating on water, and 50 cm3 of iron is totally submerged. Which has the greater buoyant force on it?
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The wood
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The iron
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Both have the same buoyant force
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Cannot be determined without knowing their densities
Correct Answer
A. The ironExplanation
Buoyant force is calculated using the volume of displaced fluid, the submerged iron will displace more fluid, therefore there will be a larger buoyant force.Rate this question:
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- 10.
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?
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The aluminum
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The lead
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Both have the same buoyant force
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Cannot be determined without knowing their volumes
Correct Answer
A. The aluminumExplanation
Aluminum is less dense than lead, therefore a 10kg piece of it must have a larger volume and displace more water. So the buoyant force on the aluminum is larger.Rate this question:
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Mar 19, 2023Quiz Edited by
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Nov 30, 2010Quiz Created by
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