# Find the Velocity

• Sep 27th 2008, 02:54 PM
dm10
Find the Velocity
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.

(a) Find the velocity of the rock after one second.

(b) Find the velocity of the rock when t=a.
• Sep 27th 2008, 03:00 PM
Jhevon
Quote:

Originally Posted by dm10
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.

(a) Find the velocity of the rock after one second.

(b) Find the velocity of the rock when t=a.

note that we obtain the velocity function by differentiating the position function.

can you do the problem now?
• Sep 27th 2008, 03:05 PM
dm10
Nope.
• Sep 27th 2008, 03:06 PM
Jhevon
Quote:

Originally Posted by dm10
Nope.

you can't find the derivative of $H(t) =10t-1.86t^2$ ?
• Sep 27th 2008, 03:50 PM
dm10
Quote:

Originally Posted by Jhevon
you can't find the derivative of $H(t) =10t-1.86t^2$ ?

If I knew how to find it, then I wouldn't be on this website.
• Sep 27th 2008, 04:02 PM
Jhevon
Quote:

Originally Posted by dm10
If I knew how to find it, then I wouldn't be on this website.

there happens to be a lot of people on this website who know how to find the derivative of that. it could also be that you do not know how to approach the problem as opposed to knowing how to approach the problem but not being able to do it.

use the power rule $\frac d{dx} x^n = nx^{n - 1}$. n is a constant here. and note that the derivative of a constant times a function is just the constant times the derivative of the function. (here you use t as the variable instead of x, of course).

and try in the future not to bite the hand that feeds you. it's silly to use that tone with someone who is trying to help you