A hollow metal sphere of mass m has an instantaneous upward acceleration 'a' when released from rest fully submerged in a liquid of density d1. If the density of the metal is d2 find the volume of the cavity in the sphere?
The net force acting on the hollow metal sphere is,
Fnet=Fb−mg
ma=Fb−mg
Volume(metal sphere)d2×a=Total volume×d1×g−volume(metal sphere)d2g
Write total volume in form of volume of metal+cavity.
(V(m)+V(c))d1g=V(m)d2(g+a).
V(c)d1g=V(m)d2(g+a)−V(m)d1g
Here, V(m)=m/d2
V(c)d1g=m(g+a)−md1d2g
V(c)=m(g+a)d1g−md2.