Mechanical energy = Potential energy + Kinetic energy
M.E of basketball = 61 + 57 = 118J
M.E of notebook = 0 + 19 = 19J
Considering the definition of mechanical energy:
Mechanical energy is that which a body or a system obtains as a result of the speed of its movement or its specific position, and which is capable of producing mechanical work. Then:
Potential energy + kinetic energy = total mechanical energy
The principle of conservation of mechanical energy indicates that the mechanical energy of a body remains constant when all the forces acting on it are conservative (a force is conservative when the work it does on a body depends only on the initial and final points and not the path taken to get from one to the other.).
Therefore, if the potential energy decreases, the kinetic energy will increase. In the same way if the kinetics decreases, the potential energy will increase.
In this case, if a ball has 57 J of potential energy and 61 J of kinetic energy. The total mechanical energy of the basketball is calculated as:
Total mechanical energy= Potential energy + kinetic energy
Total mechanical energy= 57 J + 61 J
Total mechanical energy= 118 J
Then, the total mechanical energy of the basketball is 118 J.
On the other side, a notebook sitting on a desk has 19 J of potential energy. So, the total mechanical energy of the notebook can be calculated as:
Total mechanical energy= Potential energy + kinetic energy
Total mechanical energy= 19 J + 0 J
Total mechanical energy= 19 J
Then, the total mechanical energy of the notebook is 19 J.
Learn more:
