BigMitch wrote:This is how I got my number:

Sin = opposite/hypotenuse

(sin)x(hypotenuse) = opposite

[sin(15 degrees)] x [(5280 ft/mile) x (3 mile/hr)] = opposite

sin (15 degrees) = 0.2588

[0.2588] x [15,840 ft/hr] = opposite

4099 ft/hr = opposite

Therefore, 4099 ft/hr are climbed at 15 degrees at 3 mph.

Q.E.D.

I think the grade on treadmills is measured in % not degrees...which would be vertical / horizontal.

y / x = 0.15 = inverse tangent (angle of incline)

if x is 3mph, then y = 3 * .15 = .45 mph. 0.45 mph * 5280 ft / mile = 2376 ft / hr.

Actually the hypotenuse is moving at 3mph (not horizontal) , although this doesn't make much of a difference at this grade. (2350 ft / hr would be more accurate)