In a vertical circular motion a body of mass 2kg is moving with thread of length 2 meters the change in tension when body reaches lowermost positionnto topmost position is?

At top minimum velocity should be such at least centripetal force is equal to the weight of the bodym(v)^2÷r=mgv(at a)=√grSo velocity at top most point(a) is √grAt bottom most point(b) ,by conservation of energy,we get1/2m[v(at b)]^2 = mgh+1/2m[v(at top)^]^2 {here h=2r}So,[v(at b)]^2 = 4gr + grv(at b) = √5grNow,we have,Tension at top most point(a) isT(a) =mv^2/r - mgTension at bottom most point(b) isT(b) = mv^2/r + mgFor change in tension∆T=T(b) - T(a) =m{v(b)}^2/r + mg - m{v(a)^}2/r + mg =5mg + mg - mg + mg =6mg∆T=6×2×10∆T=120 N