Respuesta :

badddiee
The mechanical energy of an object is equivalent to the sum of its potential and kinetic energy. If the helicopter is grounded, then its mechanical energy will be 20 J. If it is in the air, then its potential energy will be calculated using:P.E = mghAnd then added to the kinetic energy to obtain mechanical energy.
Brandikitts
Energy per time is called the power. It is the rate of energy. For this question, we simply divide the values. We do as follows:

Mechanical energy per time = 20 J / 2.5 s = 8 J /s