An empty plastic box of mass m is found to accelerate up at the rate of g/6 when placed deep inside water. How much sand should be put inside the box so that it may accelerate down at the rate of g/6?

Question

Philoid · Accepted Answer

Given:

Mass = m

Case I:

When it accelerates upward with acceleration =

Let B be the buoyant force.

Thus,

Case II:

When it accelerates downward with acceleration = after addition of sand of mass

Thus,

∴