Question

find momentum of a body of mass 100g having kinectic energy 500J

Answer 1

monmentum, p = m x v
so v= p/m
K.E. = 1/2 mv²
=1/2 m (p/m)²
=1/2 m x p²/m x m
=p²/2m
so, according to the question,
K.E. = 500J
⇒500 = p² / 2 x 100 
⇒p² = 500 x .2
⇒p = √100.0 = 10 
so momentum is 10 kg.m/s 

Answer 2

Given- 
Mass=100g
        =0.1
Kinetic energy=500 j
we know,
1/2×0.1×v²=500
or, 0.1×v²=500×2
or,1/10×v²=1000
or,v²=10000
or,v=√10000
or,v=100
we know that momentum of a body is=m×v
                                                         =0.1×100
                                                         =1/10×100
                                                         =10 kgm/s
Hope it helps...............