Posted by Katrina on .
If a rock is thrown upward on the planet Mars with a velocity of 17 m/s, its height (in meters) after t seconds is given by H = 17t − 1.86t^2.
(a) Find the velocity of the rock after one second.
(b) Find the velocity of the rock when t = a.
(c) When will the rock hit the surface? (Round your answer to one decimal place.)
(d) With what velocity will the rock hit the surface?

Calc 
Steve,
As on earth, v = Vo  at where a = 1.86*2 on Mars.
So, v = 17  3.72t
v(1) = 173.72 = 13.28m/s
v(a) = 17  3.72a
Since h = t(171.86t)
h=0 when t = 0 (rock thrown)
and t = 9.14 (rock hits again)
The rock will hit the surface with the same speed it had when it left: 17m/s. However, as a velocity, it's falling, so v = 17m/s