Which one among the following statements is correct?
The total mechanical energy of a system is conserved if the forces, doing work on it, are conservative.
The law of conservation of mechanical energy applies only when the net work done on a system is by conservative forces (such as gravity or an ideal spring force), for which a well-defined potential energy can be assigned; under this condition the sum of kinetic and potential energy stays constant.
If non-conservative forces (like friction or air resistance) do work, mechanical energy is not conserved — some of it is dissipated as heat, so the second option is false, and the third option (that mechanical energy always remains constant, unconditionally) is also false.
Not every force has an associated potential energy — non-conservative forces such as friction do not, since the work they do depends on the path taken, so the fourth option is false.
Hence, the correct statement is that total mechanical energy is conserved when the forces doing work are conservative.
Important Questions from Work Power Energy
The energy possessed by a body due to its change in position or shape is called
Wind turbines convert ________ energy into mechanical power.
What is represented by the product of force with displacement in the direction of force?
The rate of doing work is called:
What powers the Earth's internal heat engine?
