Question

A ping pong ball has volume v and density 1/7 th that of liquid. what force would be required to hold It completely inside the liquid??

Answer 1

Given:
ping pong ball density relative to liquid= 1/7
Volume of ball=v
let density of liquid be d
let 'g' be the acceleration due to gravity
Apparent weight of ball=weight -buoyant force.
=(m)g-(vd)g
=(vxd)xg/7 - vd/g
=-6vdg/7
the apparent weight of force is upward force. so to push it inside the water, and hold it inside a water, a force of 6vdg/7 is required