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.

 

[tomcue]

Your concept is correct. According to the equation for kinetic energy (KE=0.5mv^2), as the speed of an object increases, its kinetic energy also increases. This is because kinetic energy is directly proportional to the square of the velocity. In this case, the object's speed has doubled from point A to point B, resulting in a four-fold increase in its kinetic energy. This is a fundamental principle in physics known as the work-energy theorem, which states that the work done on an object is equal to the change in its kinetic energy. Therefore, in order for the object to increase its speed, energy must be transferred to it, resulting in an increase in its kinetic energy.