Answer:
14112 J
Explanation:
When the 72 Kg mass explodes into two, one mass is twice the other so 72/3=24 Kg
M1= 24 kg, M2= 72-24=48 kg
From law of conservation of linear momentum, the sum of initial and final momentum are equal. p=mv where p is momentum, m is mass and v is velocity. Fir this case, since the less massive piece stops, its final velocity is zero.
72*28=48v2
V2=72*28/48=42 m/s
Difference between initial and final kinetic energy will be
Therefore, from observers reference, kinetic energy of 14112 J is added