
Randall Munroe developed this "horse-drag equation" for calculation of the power needed to push through a crowd on a horse.
[1]crowd density (per square meter) x crowd weight per person (in lbs) x horse chest width (in feet) x speed
3 (in mph) = power (in watts)
He estimates that the power required to push through the crowd of orcs is 97kW, or 130 horsepower. That's around six times the maximum power output of a horse.
[2]However, what if we plug in the RW figures? A RW horse is currently a vole, so:
775 orcs/m x 0.09 lbs/orc x 0.116 ft x 5
3 mph = 1011.375
1011 watts is way too much—it's over 1.3 horsepower. I may have made a mistake by plugging in imperial figures instead of metric.
[1]:
How To, Randall Munroe, p.124.
[2]: A horse can do more than 1 horsepower for a short amount of time, as a horsepower is defined by work over a longer period of time.