Buoyancy in gases

According to Archimedes' principle, what determines the magnitude of the upward buoyant force acting on an object floating or moving through a gas?

1 pts

volume_mute

The weight of the gas displaced by the object.

The total atmospheric pressure acting down on the top of the object.

The true mass of the object measured in a vacuum.

The chemical composition of the solid material making up the object.

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Explanation

Why does a balloon filled with helium gas rise upward through the surrounding air atmosphere?

1 pts

volume_mute

The weight of the displaced air is greater than the combined weight of the balloon envelope and the helium inside.

Helium molecules possess negative mass and are naturally repelled by Earth's gravity.

The balloon structure completely eliminates the effects of atmospheric pressure.

Helium gas generates a miniature vacuum inside the balloon envelope that pulls it upward.

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Buoyant Force vs. Altitude

1 pts

volume_mute

An unanchored toy balloon filled with helium rises high into the sky. As it reaches higher altitudes where the outside air density decreases, what happens to the buoyant force acting on the balloon?

The buoyant force decreases because a given volume of thinner air weighs less.

The buoyant force increases because there is less atmospheric pressure pushing down on the top.

The buoyant force remains perfectly constant because the balloon's volume doesn't change.

The buoyant force drops instantly to zero the moment the balloon leaves sea level.

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Calculating Buoyancy in Air

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A rigid, sealed sphere has a total volume of \(10\text{ ft}^3\). If the weight density of the surrounding air is exactly \(0.08\text{ lb/ft}^3\), calculate the upward buoyant force acting on the sphere.

Answer = (1)

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Explanation

Fill in the blank to complete the rule governing floating objects in the atmosphere

1 pts

A rising hot-air balloon will stop ascending and hover at a constant altitude when its total downward weight becomes exactly equal to the upward (1) force exerted by the air.

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Buoyant Force of Displaced Atmospheric Air

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A large balloon has an external physical volume of \(50\text{ ft}^3\). If the weight density of the ambient air at sea level is exactly \(0.08\text{ lb/ft}^3\), what is the total upward buoyant force exerted by the air on the balloon?

Answer = (1)

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Net Force Action on Atmospheric Objects

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volume_mute

A rigid fiberglass sphere filled with standard air weighs exactly \(12\text{ lb}\) in a vacuum. When it is placed into the outside atmosphere, it displaces a volume of air that weighs \(2\text{ lb}\). What is the net vertical force acting on the sphere, and in which direction?

10 lb downward

10 lb upward

14 lb downward

0 lb (neutral equilibrium)

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Explanation

Why does heating the air inside a hot-air balloon cause the balloon to rise up into the cooler surrounding atmosphere?

1 pts

volume_mute

Heating causes the air molecules to expand outward from the bottom opening, making the air inside less dense than the outside air.

Heating destroys the mass of the internal air molecules, eliminating their gravitational weight completely.

Hot air molecules carry an inherent electrical charge that is repelled by the ground.

The hot air increases the mechanical strength of the balloon envelope fabric to resist atmospheric pressure.

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Explanation

Match each physical condition of an object in the atmosphere to its corresponding vertical mechanical movement

1 pts

To complete the line match

Click on an item in the first group
Click on the match in the second group

To delete a match, double click on a line

Conditions

The total weight of the balloon system is greater than the weight of the displaced air

The total weight of the balloon system is exactly equal to the weight of the displaced air

The total weight of the balloon system is less than the weight of the displaced air

Movements

The balloon descends toward the ground

The balloon hovers stationary at a constant altitude

The balloon ascends higher into the sky

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Explanation

Determine if the following scientific statement is true or false

1 pts

volume_mute

"A helium-filled weather balloon will continue to rise indefinitely until it escapes Earth's atmosphere and enters the complete vacuum of outer space."

true

false

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According to Archimedes' principle, what determines the magnitude of the upward buoyant force acting on an object floating or moving through a gas?

Correct Answer

Explanation

Why does a balloon filled with helium gas rise upward through the surrounding air atmosphere?

Correct Answer

Explanation

Buoyant Force vs. Altitude

Correct Answer

Explanation

Calculating Buoyancy in Air

Correct Answer

Explanation

Fill in the blank to complete the rule governing floating objects in the atmosphere

Correct Answer

Explanation

Buoyant Force of Displaced Atmospheric Air

Correct Answer

Explanation

Net Force Action on Atmospheric Objects

Correct Answer

Explanation

Why does heating the air inside a hot-air balloon cause the balloon to rise up into the cooler surrounding atmosphere?

Correct Answer

Explanation

Match each physical condition of an object in the atmosphere to its corresponding vertical mechanical movement

Conditions

Movements

Correct Answer

Explanation

Determine if the following scientific statement is true or false

Correct Answer

Explanation

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