What is acceleration of ping pong in mercury?

Question

Standard ping pong is 2.7 gram, 40 mm diameter ball.
Estimate initial acceleration of the ball if it is submerged
in mercury and then released.

Note the word 'estimate'.

Answer 1

Nice question dude.

As the viscous drag on a solid substance moving inside a fluid is directly proportional to its velocity,a stationary submerged ball will start with a initial acceleration of "g" that is 9.8m/s,because the only force acting on it initially is the gravity.Its acceleration will then decrease until it becomes zero and it will attain a constant velocity which we call "Terminal Velocity".

Answer 2

there r three forces acting on ping pong ball
1)gravitational force m*g
2)viscous force
3)buoyancy v*d*g
so acc would be(not considering viscous force)
g(d*v-m)=ma
a=g(d*v-m)/m