The Energy is Kinetic Energy.
Kinetic Energy = 1/2*mv², Where m is mass in kg, v is velocity in m/s
Energy is 33750 Juoles, v = 30m/s
1/2*mv² = E
1/2*m*30² = 33750
m = (2*33750) / (30²) Using a calculator
m = 75 kg
Mass of object is 75 kg.
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