Energy is not conserved when a moving object slows to a stop?

Answer 1

Energy is always conserved, when slowing down an object until it stops, there must be an external force. The potential energy of the object had changed itself in to heat sound and/or light energy while is slowing down because of the friction.

An interesting point of this questions is that when the object is in space, moving towards you at a fast speed, the light reflected back to you would be shrinked, its called a blue shift. the other way around would be a red shift. Since when certain thing is moving in empty space and its not changing its course or any thing just floating and flying, there isn't energy in it. law of inertia stands that point. but when the light is shrinked, the wavelength of it is shrinked. the wavelength of a wave determinds its energy, then in our case, we just created bunch of energy out of no where.

Answer 2

Yes. Energy is ALWAYS conserved. In this case, there would probably be friction, meaning the movement energy gets converted to heat energy.

Answer 3

Kinetic energy is changed to thermal energy.

Answer 4

never