What is the energy of the 30 kg skateboarder at 2 m off the ground traveling at 3 m/s?

1) The kinetic energy of an object is given by:

where m is the object's mass and v its speed.

By using this equation, we find the initial kinetic energy of the skateboarder:

and the final kinetic energy as well:

So, her change in kinetic energy is

2) The work-energy theorem states that the work done to increase the speed of an object is equal to the variation of kinetic energy of the object:

Therefore, the work done by the skateboarder is