# Davis formula application

So I stumbled upon the Davis formula for trains while doing some researches about my project but I don't know how to apply it (programmatically) :

Let's say for example this variant : $$R'=1.3+\frac{29}{w}+.045v+\frac{.0005av^2}{wn}$$

Where -$$R'$$ is the rolling resistance in lb/ton, $$w$$ is the axle weight in us-tons, $$v$$ is the speed in mph, $$a$$ is the cross-sectional variable in square feet and $$n$$ is the number of axles in car.

1. I want to know how to convert the result from lb/ton to Newton?

2. I also want to know if I should apply this formula to the locomotive of the train and add it to all the other cars of the train then sum the result?

• Perhaps you should tell us what the "Davis formula for trains" is, and give us a reference to where you found it? – mike stone May 15 '19 at 15:58
• okay so here is the thing, i'm currently a student and working on a train simulator project as an intern, the problem is that i'm not familiar with physics and i don't even know from where to start, the formula i found originate from here [link] (elvastower.com/forums/…) and it is used to calculate the rolling resistance of the train, i honestly just want to simulate using c# a basic and correct behavior of the train to accelerate and brake for the meantime. – Gotenks00 May 16 '19 at 7:23