A person of mass (M=90 ~kg ) standing on a smooth horizontal plane of ice throws a body of mass (m=10 ~kg ) horizontally on the same surface. If the distance between the person and body after (10 ~s ) is (10 ~m ), then the KE of the person (in ( J )) is

Step-by-step solution

According to the question body travels (10 ~m ) in (10 ~s ), hence its velocity is given as (v= 10 ~m 10 ~s =1 ~m / s ) ( ) According to conservation of linear momentum. Initial total moment (= ) Final total moment (0+0=M v^ +m v ) where, (v^ ) is velocity of person. ( aligned & v^ =- m v M =- 10 1 90 =- 1 9 ~m / s & Kinetic energy of person = 1 2 M v^2 & = 1 2 90 (- 1 9 )^2=0.55 ~J aligned )