Test: Buoyancy - Mechanical Engineering MCQ

Explanation: Weight of the block=ρ*g*Volume=850*9.81*7*3.5*1=204.29 kN
Volume of
water displaced= Weight of water displaced/weight density of water
= 20.825 m³.
h=20.825/3.5*7=0.85 m.

Explanation: Weight of water displaced=Weight of stone in air – Weight of stone in water
=250
Volume of water displaced=Volume of stone=250/9.81*1000=0.025 m³.

Explanation: Weight of water displaced=Weight of stone in air – Weight of stone in water
=375
Volume of water displaced=Volume of stone=375/9.81*1000=0.038 m3
Density of stone= mass/volume=650/9.81*0.038=1733 kg/m³
specific gravity= Density of stone/Density of water=1.73.

Explanation: Weight of stone in air = Weight of water displaced+Weight of stone in water
= 9.81*1000*2.7*3.8*2.5+2500=254.12 kN.

Explanation: Total Bouyant force=Force of bouyancy due to water+Force of bouyancy due to mercury
For equilibrium, Total bouyant force= Weiht of body
1000*9.81*0.6*V + 13.6*1000*9.81*0.4*V=ρ*g*V
ρ=6040 kg/m³.

Explanation: The principal cause of action of buoyant force on a body submerged partially or fully in fluid is the force equal in magnitude to the weight of the volume of displaced fluid.

Explanation: By changing the shape of an object it can be made to float on a fluid even if it is denser than that fluid. This principle is used in ship building.

Explanation: Buoyant force acting on the airship decreases as it rises in the air as air at higher altitude becomes rarer and its density decreases.

Explanation: As balloon rises in air, pressure acting on it reduces and therefore its volume increases. Also, a rising balloon ceases rising when it and the displaced air are equal in weight.

Explanation: To dive, the submarine tanks are opened to allow air to exhaust, while the water flows in. When the weight has been balanced so the overall density of the submarine is equal to the water around it, it has neutral buoyancy and hence will go down.