Does Kinetic energy really exists?

Question

I'm wondering if the kinetic energy that in Classical Mechanics is (1/2)mv^2 really exists. If we change the frame of reference the velocity v changes, so do the KE. So should we have for instance zero KE in case of a frame of reference that the body has zero velocity. Is this right?

Answer 1

No matter what reference we are in KE exists, whether it is relativistic or non relativistic.

Answer 2

Yes kinetic energy really exists. Look up the defintion of it in a dictionary. It will probably say that kinetic energy is the energy of motion (not potential motion obviously) and motion is a type of energy so in that sense it does exist.
And yes if there is zero velocity there is zero KE. This is because it is not in 'motion' which is what the velocity refers to. If we change the frame of reference so that m=0 making KE =0 does it mean KE in general does not exist. I mean really.

Answer 3

If i remember correctly you cannot use frames of reference when calculating kinetic energy because if you do and take an item going at 10m/s and take that as your frame of reference then the entire universe would be moving with 10m/s velocity giving you 2 massively different Ke values. I could be talking crap though so wait to see what opthers say :)

Answer 4

You are saying that if you are moving at the same speed as the object your measuring, the object in question would have 0 KE...This is true...You have to understand though that KE is just a measurement of energy relative to the velocity of one object to another...

Answer 5

Does exists?

Yahoo questions just keep getting worse.

Smash your car into a tree and report back with the delta V numbers related to the collision.

Answer 6

yep! then it has potential energy instead!