A running man has the same kinetic energy as that of a boy of half his mass. The man speeds up by 2 ms^(-1) and the boy changes his speed by x m s^(-1) so that the kinetic energies of the boy and the man are again equal. Then x in m s^(-1) is

A running man has the same kinetic energy as that of a boy of half his

1.	A running man has the same kinetic energy as that of a boy of half his mass. The man speeds up by 2 ms^(-1) and the boy changes his speed by x m s^(-1) so that the kinetic energies of the boy and the man are again equal. Then x in m s^(-1) is
Answer» 1/2 `2sqrt(2)` `SQRT(2)` `2` SOLUTION :Let the MASS of man be m. Therefore, mass of the BOY is `m/2` As. `1/2 mv_1^2 = 1/2(m/2) v_2^2 :. v_1= (v_2)/(sqrt2)` `1/2 m(v_1 + 2)^2 = 1/2[m/2 (v_2 + X)^2]` `:. (v_1 + 2)^2 = ((v_2 + x)^2)/(2) " or " v_1 + 2 = (v_2+ x)/(sqrt2)` But `v_1 = (v_2)/(sqrt2) :. x/(sqrt2) = 2 " or " x = 2sqrt(2)`.