Buoyancy

Assertion : For a floating body to be in stable equilibrium, its centre of buoyancy must be located above the centre of gravity. Reason : The torque produced by the weight of the body and the upthrust will restore body back to its normal position, after the body is disturbed.

Let T represent the true weight of a body, B the force of buoyancy on the body when immersed in a liquid. A represents the apparent weight of the body and W be twice the weight of liquid displaced by te body. Then which of the following relation is correct?

Statement I: A needle placed carefully on the surface of water may float, whereas the ball of the same material will always sink. Statement II: The buoyancy of an object depends both on the material and shape of the object.

A hot air balloon (mass M) has a passenger (mass m) and is stationary in the mid air. The passenger climbs out and slides down a rope with constant velocity u relative to the balloon. (a) Show that when the passenger is sliding down, there is no change in mechanical energy (kinetic + gravitational potential energy) of the system (Balloon + passenger). Calculate the speed of balloon. (b) Calculate the power of the buoyancy force on the system when the man is sliding. For easy calculation, assume that volume of man is negligible compared to the balloon. (c) If buoyancy force is doing positive work, where is this work done lost? You have proved that sum of kinetic and potential energy of the system remains constant

Which of the following statement are not true about shark? a. The skin is tough and covered with placoid scales. b. They possess a swim bladder which regulates buoyancy. c. the tail of shark is heterocercal. d. Ampulla of lorenzini present in the snout of shark is thermoreceptor. e. it has five pairs of gill slits covered by operculum.

Assume the density of brass weights to be 8 g cm^(-3) and that of air to be 0.0012g cm^(-3) . What fractional error arises from neglecting buoyancy of air in weighing and objecte of density 3.4 g cm^(-1) on a beam balance?

When a layer of air receives enough heat from Earth's surface, it expands and becomes less dense. This layer is then pushed upward by buoyancy. The cool and heavy air sinks under this layer. This cycle repeats with the re-heating of the cool air. The phenomenon described in the preamble is known as

A wooden rod weighing 25N is mounted on a hinge below the free surface of water as shown. The rod is 3m long and uniform in cross section and the support is 1.6m below the free surface. At what angle alpha rod is in equilibrium? The cross-section of the rod is 9.5 xx10^(-4)m^(2) in area. Density of water is 1000kg//m^(3) . Assume buoyancy to act at centre of immersion. g=9.8m//s^(2) . Also find reaction on the hinge in this position. .