All AP Physics 2 Resources
Example Questions
Example Question #11 : Fluids
A semi-hollow, spherical ball with an empty volume of is submerged in water and has an initial mass of . The ball develops a leak and water begins entering the ball at a rate of . How long does it take before the buoyant force on the ball is equal to the gravitational force?
We are asked when:
Now we need to develop an expression for the mass in the ball using the rate at which water enters the ball:
Where:
Plugging this into expression (1):
Rearranging for time, we get:
Plugging in our values, we get:
Example Question #541 : Ap Physics 2
Which of the following statements best describes the buoyant force on an object submerged in water?
The buoyant force is equal to the weight of the object submerged in water.
None of these accurately describe buoyant force.
The buoyant force is equal to the weight of the water displaced by the object.
The buoyant force is equal to the weight of all of the water.
The buoyant force is equal to the volume of water displaced by the object.
The buoyant force is equal to the weight of the water displaced by the object.
The correct answer is that the buoyant force is equal to the weight of the water displaced by the object.
It is an upward force that is exerted on the object because of the volume of fluid displaced by that object.
Example Question #22 : Buoyant Force
What mass of helium would be needed to lift a balloon and a camera off of the ground?
This will be impossible
Combining equations:
Plugging in values:
Solving for
Example Question #23 : Fluid Statics
A block weighing is suspended by a string and submerged in water. The block is times denser than water. What is the apparent weight of the block in water?
The correct answer is
We know that the block is five times denser than the water. This means that a weight of the block would be the buoyant force which can be calculated as the following:
We can subtract the of weight from the original weight of the block which was
We obtain
Example Question #21 : Buoyant Force
A block with a volume of sinks to the bottom of a water tank. What is the buoyant force on the block?
There is no buoyant force on the block
The correct answer is because although the block has sunk, there is still a buoyant force. This buoyant force is the result of the block displacing a volume of water, equal to the block's volume. The weight of the water volume displaced is because was displaced. The weight of is which is equal to the buoyant force on the block.
Example Question #21 : Fluids
An paint can of volume is floating on top of a lake, but water is slowly leaking in. Determine the volume of water present in the can when it finally sinks.
None of these
When the can sinks, the net force of the water in the can plus gravity will be greater than the buoyant force. So the point of sinking is when they are equal.
Solving for
Plugging in values:
Using the density of water,
Example Question #26 : Fluid Statics
Seawater density:
A baseball has a mass of and a circumference of . Determine what percentage of a baseball will be submerged when it is floating in seawater after a home run?
None of these
Solving for
Plugging in values
If the circumference is , it is
Example Question #27 : Fluid Statics
A ship has mass . What volume of water would it need to be able to displace in order to be able to float?
Density of seawater:
None of these
Solving for
Example Question #28 : Fluid Statics
Determine the volume of water that needs to be displaced in order for a man to be able to float.
None of these
When floating, the net force on the man is zero. The net force is made up of buoyant force and gravity.
Solving for volume
Plugging in values:
Example Question #23 : Fluid Statics
A ship has mass . What volume of water would it need to be able to displace in order to be able to float?
None of these
Solving for
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