A 42-Kg Object, Initially at Rest, "Explodes" into Three Objects of of Equal

Multiple Choice

A 4.2-kg object, initially at rest, "explodes" into three objects of equal mass. Two of these are determined to have velocities of equal magnitudes (5.0 m/s) with directions that differ by 90°. How much kinetic energy was released in the explosion?

A) 70 J
B) 53 J
C) 60 J
D) 64 J
E) 35 J