Question

13. A 60 kg boy lying on a surface of negligible
friction throws horizontally a stone of mass 1
kg with a speed of 12 m/s away from him. As
a result with what kinetic energy he moves back​

Answer 1

Answer:

As a  kinetic energy he moves back 1.2 J

Explanation:

According to the problem the weight or mass of the boy is 60 kg

therefore let mass= m= 60 kg

he throws a stone having 1 kg and his speed was 12 m/s

now we know that ,

initial momentum= final momentum

therefore putting all the values,

0 = 60 x v + 1 x 12

=> - 60 v = 12

=> v= -1/5

Now the kinetic energy he moves back,

Kinetic Energy= 1/2 m v^2

                         = 1/2 60 x (1/5)^2

                         =  1.2 J