855 B
855 B
Work Energy and Power
Formula is: K=\frac{1}{2}mv^2
K in joules
m in kg
v in m/s
- Kinetic energy is scalar, only magnitude and never negative.
- Because velocity is squared, changing speed affects energy more than changing mass.
- For a system of objects, total kinetic energy is the sum of each object's kinetic energy.
- Different observers in different reference frames can calculate different kinetic energies.
If a dude standing on earth sees a 1kg ball travelling at 10m/s, he'll calculate it as 50J. If a dude taped to the ball calculates it he'll calculate 0J. If a theoretical god looked at it from a universal standpoint he'd probably calculate like 1*10^6 Joules due to Earth orbiting the sun and the solar system orbiting the Milky Way.
In a collision, total energy before and after is consistent in the observers frame.