A battery of six cells each of e.m.f. 2V and internal resistance `0.5Omega` is being charged by D.C. mains of e.m.f. 220V by using an external resistance of `10Omega` what will be the charging current.

Explanation

Let m be the mass of a single particle before any of the collisions. The mas of particles formed after collidions must be 3m. In free space, no external forces act on any of the particles, their total momentum remains conserved.
Applying principle of conservation of momentum, we have
`sum vec(p)_("initial") = sum vec(p)_("final") rarr mv_(0)hat(i)- 3mv_(0)hat(j) + 5mv_(0)hat(k) = 3m vec(v)`
`vec(v)= 1/3v_(0)(hat(i) - 3hat(j) + 5hat(k))m//s`