MagLev train energy requirements

[zuignapje]

In class I've built a Maglev train. In the report we should also cover the theory behind the Maglev train though.
I came across the Transrapid train in Germany. I have a question concerning a formula we used in the report.

Homework Statement

We used the following formula: P = Cw×Afront×(density of surrounding air)/2
(see http://en.wikipedia.org/wiki/Transrapid#Energy_requirements)
Our teacher wants us to tell what this formula actually derives from (such as p=F/A and F=m×a)
We are however unable to solve this.

Homework Equations

p=F/A, F=m×a and probably many more

The Attempt at a Solution

We didn't get much further than what is already said above :/
Thanks in advance.

 

[jbsteele]

The formula P = Cw×Afront×(density of surrounding air)/2 is derived from the equation P=F/A, where P is the power (in watts), F is the force, and A is the area. The force is derived from the equation F=m×a, where m is the mass of the train and a is the acceleration. The front area of the maglev train is Afront, the density of the surrounding air is the density of the air, and Cw is a drag coefficient that takes into account several factors such as the shape of the train, its speed, etc.