No. Energy has an ASSOCIATED mass. There is no such thing as mass-to-energy conversion, or energy-to-mass conversion. In a nuclear reaction, for example, BOTH mass and energy are CONSERVED. For a more detailed explanation, check the Wikipedia article on "binding energy".
Any time there is an energy conversion, a certain amount of one type of energy gets reduced, and another type of energy increases. The amounts lost and gained are the same, so total energy is conserved.
Down conversion is a word related to physics, it is simply a concept of the interaction of a photon and a medium which is used to convert two photons of lower frequencies such that energy is conserved.
No. Total energy is always conserved, but not so mechanical energy.
no it's not cuz if there is friction energy wont be conserved
no it's not cuz if there is friction energy wont be conserved
Momentum is conserved in a collision. If two cars have the same mass and are traveling at the same speed and collide headfirst, the momentum of both cars cancel each other out and they will be motionless. If one has greater speed or mass than the other, it will still have the difference in momentum after the collision.
Total energy is always conserved. What is lost is that usually, some useful energy is converted into unusable energy - for example, heat that is spread out.
Therefore energy is conserved.
Not really, no.
Usually some energy is wasted, yes. Energy is not "lost" in the sense of conservation of energy; energy is always conserved. However, useful energy gets converted into unusable energy all the time.
Acceleration is not conserved. Energy can not be created nor destroyed. Mass and momentum are both conserved through a set time.