an object is floating in a beaker of water. the beaker starts accelarating upwards. does the postition of the object change?
Answers
Answer:
Explanation:
The buoyant force acting on an immersed body is equal to the weight of the fluid displaced by it, if the fluid is in rest. In this case, the fluid is accelerating upwards so the buoyant force must also provide the displaced fluid force to accelerate. Therefore, buoyant force will be fVρg
eff
where V = volume of body and f = fraction of volume of body immersed in fluid and g
eff
=g+a=1.5g.
When fluid is at rest: f=1−0.4=0.6, so 0.6Vρg=Vρ
b
g where ρ
b
is the density of the block.
⇒ρ
b
=0.6ρ.
In the second case: 1.5fVρg=Vρ
b
g+Vρ
b
a=1.5Vρ
b
g⇒fρ=ρ
b
⇒f=0.6.
Thus, the fraction of immersed volume remains the same.
Body will float with 40% of the volume above water surface.
When the beaker of water is allowed to fall freely, apparent weight of the breaker starts accelarating upwards becomes zero i.e. body exerts no force on water. Hence no water is displaced due to weight of the position So buoyant force i.e. upthrust will also become zero.