Question

At what speed a body of mass 1 kg will have a kinetic energy of 1 J

it is a numerical

Answer 1

We know that 

K.E = 1/2 m v²

We'll replace K.E i.e kinectic enerygy by 1 J and mass (m) by 1 kg (given in the question)

1 = 1/2 * 1 * v²

2 = v² (take 2 to the other side)

v = √2

v = 1.414 m/s