Increase in speed, increase in energy

[MechaMZ]

Homework Statement

an 5kg object speed up from 5m/s(point A) to 10m/s(point B)

at point A, the energy is 0.5mv² = 0.5(5)(5)² = 62.5J
at point B, the energy is 0.5mv² = 0.5(5)(10)² = 250J

I don't not sure why the energy in the object is increased when it speeds up from point A to point B. suppose the energy in the object should be taken up to increase it's speed isn't?

or my concept is wrong?

 

[Delphi51]

You have calculated the kinetic energy, the energy due to speed. The greater the speed, the greater the kinetic energy.

In a real situation some other type of energy would have to decrease to free up the energy needed to increase the speed.