a car weighs 100kg and has Velocity 0. it accelerates and its speed become 10m/s. its kinetic energy would be 100*10*10/2=5000j.
from another view car is at rest and the world accelerates and has now 10m/s speed.
as energy must be constant it should be:5000=10*10/2*(world mass except car) world mass except car=100kg?
am i using conservation of energy in wrong way, or i cant have that point of view?