# position function

• Oct 24th 2007, 06:17 PM
JDG1317
position function
I Wasn't sure if this is the right place to ask this but it is my Calc 1 homework so here goes:

It don't really have a problem doing the mathematics of these problems but it just doesn't seem logically correct to me.

It makes sense to me in "Falling object" problems that the position function would be s(t)=-16t^2 - initialvelocity + initialposition

But I came acrossed a problem that involves a projectile shot upwards that says to use the same position function.

Since the falling object is accelerating and the projectile is deccelerating, How can they use the same function?
• Oct 24th 2007, 07:21 PM
Jhevon
Quote:

Originally Posted by JDG1317
I Wasn't sure if this is the right place to ask this but it is my Calc 1 homework so here goes:

It don't really have a problem doing the mathematics of these problems but it just doesn't seem logically correct to me.

It makes sense to me in "Falling object" problems that the position function would be s(t)=-16t^2 - initialvelocity + initialposition

But I came acrossed a problem that involves a projectile shot upwards that says to use the same position function.

Since the falling object is accelerating and the projectile is deccelerating, How can they use the same function?

deceleration is a form of acceleration (it is in the opposite direction). both a falling object and an object shot upward will experience the same acceleration, namely, the acceleration due to gravity pulling the object back to Earth
• Oct 25th 2007, 03:34 AM
JDG1317
It finally clicked that for the falling object I plug in a negative initial v, and for the projectile a positive initial v. Dumb question. I don't know why I could not realize that last night. Thank you for the help.