Find out the elongation in block. If mass area of cross-section and young modulus of block are m, A and y respectively.

Explanation

Acceleration, `a=(F)/(m)` then `T=m'a` where `rArr m' = (m)/(l)x`
`T=(m)/(l)xx(F)/(m)=(Fx)/(l)`
Elongation in element `'dx'=(Tdx)/(Ay)`
totoal elongation , `delta=underset(0)overset(l)int(Tdx)/(Ay) d=underset(0)overset(l)int (Fxdx)/(Aly)=(Fl)/(2Ay)`