# Thread: Help with calculus problem

1. ## Help with calculus problem

A bocce ball is accidentally dropped from a building 98m high. How long does it take for the bocce ball to hit the ground, given that the acceleration due to gravity is 9.8 meters per second per second?

I took
s(t)=-4.9t^2 + 9.8 = 0
Solved for t
-4.9t^2 = -9.8
t^2=2
t=sqrt(2)=1.414 seconds.

I had to enter my answer into a computer checking system, and it says that my answer is wrong. What am I doing wrong?

2. Your initial condition has the decimal point in the wrong location.

3. ## ?

Sorry if this seems like a silly question....but which part of my equation has a decimal in the wrong area? Where is the decimal supposed to be???

Thanks!

4. The basic equation you use to solve these problems is:

$y=y_{0}+v_{0y}t-\frac{g}{2}\,t^{2}$,

correct? You have correctly plugged in $g$ and $v_{0y}=0$, and you are correctly solving for the $t$ when $y=0$. However, your initial condition for the position, $y_{0}=98$, not $9.8$. Now do you see it?