What is the name of a system that converts thermal energy into a form of useful mechanical or electrical energy?
incubator
heat engine
centrifuge
vacuum column
spectrophotometer

Option (b) is the correct answer.

Explanation:

A heat engine is a device which provides heat to the substance placed inside it and vibration between its particles increases. As a result, kinetic energy increases which results in the formation of useful mechanical or electrical energy.

Thus, we can conclude that heat engine is the name of a system that converts thermal energy into a form of useful mechanical or electrical energy.

the moving of the box is a result of centripetal force. think of that  as a car or a truck in this case creates a turn, the force of friction performing upon the turned wheels of the car runs centripetal force obligatory for circular motion for the things inside it.