Recent content by denafoster

Thanks for your help today. :smile:

I'm guessing that something needs to be set to equal zero . . . but forgive me, I'm still a little lost.

It would be zero.

I am stuck on the final part of the question, I know how to solve it using a physics formula . . . but not with the derivative.

There was a previous part to the question which I have the answer for : What is the velocity of the dart one second after it is shot upward? v'(t) = -9.8t + 20 = -9.8(1) + 20 = 10.2 m/s What is the Maximum height that the dart reaches ? velocity will be zero at 2.0408 seconds...

A dart is shot straight up from 1.5m above ground level. The distance d, in meters, the dart is above ground at time t, in seconds, is : d(t) = -4.9t^2 + 20t + 1.5 For how many seconds is the dart in the air?