P=Drawbar pull of locomotive in lbs.
R=Train resistance in lbs.

V1 Terminal velocity in miles per hour.
V2=Initial velocity in miles per hour.

(P-R) per ton of train (including locomotive) when
positive in value is the net power available for use in over-
coming grade resistance at maintained speed. Also rep-
resents the power available for acceleration.

(P-R) per ton of train (including locomotive) when
negative is the assistance that must be received from de-
scending grades in order to maintain the given velocity.
When such assistance is not received it becomes a retard-
ing resistance.

For (P-R) for other than level grades subtract from
its value per ton of train for level grades the grade resist-
ance in pounds per ton of train.

The distance in feet required to accelerate from a given velocity to another equals 70 (V,V,) divided by the mean of (P-R) per ton of train for the two velocities.