Buoyant Force
Trending Questions
What is the centre of buoyancy? State its position for a floating body with respect to the centre of gravity of the body.
It is easier to lift a heavy stone under water than in air. Explain.
A body dipped into a liquid experiences an upthrust. State two factors on which upthrust on the body depends.
What are the factors on which the upthrust depends?
The pressure at a depth of 200 m below the surface of the sea, will be
The density of seawater is 1024 kg/m3.
What is upthrust? Write its unit.
What is the cause of upthrust? At which point it can be considered to act?
Will a body weigh more in air or in vacuum when weighed with a spring balance ? Give a reason for your answer.
Upthrust is equal to the weight of the displaced liquid.
True
False
Prove that the loss in weight of a body when immersed wholly or partially in a liquid is equal to the buoyant force (or upthrust) and this loss is because of the difference in pressure exerted by liquid on the upper and lower surfaces of the submerged part of the body.
How is the upthrust related to the volume of the body submerged in a liquid ?
In what direction and at what point does the buoyant force on a body due to a liquid, act ?
Upthrust on a body depends on
A. The acceleration due to gravity, the density of the liquid
B. The volume of the body immersed in the liquid.
Only 'A'
Only 'B'
Both `A’ and `B’
None
You are provided with a hollow iron ball A of volume 15 cm3 and mass 12 g and a solid iron ball B of mass 12 g. Both are placed on the surface of water contained in a large tub.
(a) Find upthrust on each ball.
(b) Which ball wil sink ? Give reason for your answer. (Density of iron = 8.0 g cm−3)
State the SI unit of buoyant force.
Upward force acting on a body submerged in a liquid is called
For a floating body, its weight W and upthrust FB on it are related as :
(a) W>FB
(b) W<FB
(c) W=FB
(d) nothing can be said.
An incompressible liquid flows through a horizontal tube as shown in the following fig. Then the velocity v of the fluid is 1 m/s
3.0 m/s
1.5 m/s
A body weighs 450 gf in air and 310 gf when completely immersed in water. Find :
(i) the volume of the body,
(ii) the loss in weight of the body, and
(iii) the upthrust on the body. State the assumption made in part (i).
A small block of wood is held completely immersed in (i) water, (ii) glycerine and then released. In each case, what do you observe ? Explain the difference in your observation in the two cases.
A body of volume 100 cm3 weighs 5 kgf in air. It is completely immersed in a liquid of density 1.8 ×103 kg m−3. Find :
(i) the upthrust due to liquid and
(ii) the weight of the body in liquid.
(iii) the upthrust on the body.
State the assumption made in part (i).
Describe an experiment to show that a body immersed in a liquid appears lighter than it really is.
Fig. shows the same block of wood floating in three different liquids A, B and C of densities ρ1, ρ2 and ρ3 respectively. Which of the liquid has the highest density? Give reason for your answer.
A block of wood is just floating on water, what will happen to the block if the temperature of the water is increased?
Rises up
Sinks
Stays the same
Starts burning
Draw a diagram to show the forces acting on a body floating in water with its some part submerged. Name the forces and show their points of application. How is the weight of water displaced by the floating body related to the weight of the body itself ?
State the condition under which the body sinks, when it is immersed inside the liquid. Consider ρ to be the density of the block and ρL to be the density of the liquid.
ρ > ρL
ρ < ρL
ρ = ρL
ρ ≤ ρL
Explain the following :
(a) Icebergs floating in sea are dangerous for ships.
(b) An egg sinks in fresh water, but floats in a strong salt solution.
(c) A toy balloon filled with hydrogen rises to the ceiling, but if filled with carbon dioxide sinks to the floor.
(d) As a ship in harbour is being unloaded, it slowly rises higher in water.
(e) A balloon filled with hydrogen rises to a certain height and then stops rising further.
(f) A ship submerges more as it sails from sea water to river water.
A body experiences an upthrust F1 in river water and F2 in sea water when dipped up to the same level. Which is more F1 or F2 ? Give reason.
A metal solid cylinder tied to a thread is hanging from the hook of a spring balance. The cylinder is gradually immersed into water contained in a jar. What changes do you expect in the readings of spring balance ? Explain your answer.
