Final answer:
Negative mechanical work is when the net torque and angular motion are in different directions, often resulting in the removal of mechanical energy from the system and its conversion into thermal energy.
Step-by-step explanation:
Negative mechanical work involves a situation where the net torque and angular motion are in different directions. When an object experiences a force that applies a torque not aligned with its current direction of rotation, it causes a kind of negative work on the object, which can remove energy from it, typically in the form of mechanical energy.
The non-conservative damping force, which removes energy from a system, often converts mechanical energy into thermal energy. Thus, negative work is associated with energy transfer out of the system. This is in contrast to positive work, where energy is transferred to the system.