864 J
In order to calculate kinetic energy the mass of the moving body and it's velocity must be known. In this case the mass is 48 kg and the velocity is 6 m/s. The formula for kinetic energy is:
Kinetic Energy = 1/2 * (Mass) * (Velocity^2)
= 1/2 (48 kg) * ((6 m/s)^2)
= 864 kg* (m/s)^2 = 864 J