A `4.0 kg` block is suspended from the celling of an elevator through a string having a linear mass density of `1.6 xx 10^(-3) kg//m`. Find (a) speed (with respect to the string) with which pulse can proceed on the string it he elevator accelerates up at the rate of `6 m//s^2`. (b) in part (a) at some instant speed of lift is `40 m//s` in upward direction, then speed of the wave pulse with respect to ground at that instant is (Take `= 10 m//s^(2)`)
