As we know the formula of kinetic energy is
[tex]KE = \frac{1}{2} mv^2[/tex]
here given that
KE = 150,000 J
mass = 120 kg
we can use this to find speed
[tex]150,000 = \frac{1}{2} * 120 * v^2[/tex]
[tex]v^2 = 2500[/tex]
[tex]v = 50 m/s[/tex]
So speed of above object is 50 m/s