If a rock is thrown upward on the planet Mars with a velocity of 10 m/s, its height (in meters) after t seconds is given by H = 10t − 1.86t^2

Find the velocity of the rock when t=a.

The velocity function will be the derivative of the position function given...so

H ' = 10 - 2(1.86)t

When t = a, we have

H ' (a) = 10 - 2(1.86)(a) = [ 10 - 3.72a ] m / s