# Given Velocity formula and told to find acceleration, I need help please. [closed]

I tried to do this problem by taking the derivative and it did not get me the right answer. I also tried the Vdv=Ads integration and could not get the right answer. Please Help

• What's with the down votes? This is a clearly asked question. Commented Jan 29, 2014 at 5:36
• @Keith: the aim of this site is to become a reservoir of knowledge of interest to future students of physics (or anyone else interested in physics). Doing someone's homework for them does not contribute to this goal. Commented Jan 29, 2014 at 8:04

The correct formula to use would be $a = dv/dt = dv/ds \cdot ds/dt = dv/ds \cdot v$. Integration is not the right way to go about using this. Since you are given a formula for $v(s)$, simply compute the derivative at $s=5m$, and multiply that derivative by the value of v itself at $s=5m$.

• That did get me the right answer. but I do not know why you did this, can you please explain? Commented Jan 29, 2014 at 4:37
• The fact that $v$ is a function of $s$ means there are certain regions of space where go slowly and others where you go quickly. If you move into a region where your speed is higher, you will accelerate. Your acceleration will be equal to the product: (how much faster you go once you are in the new region) * (how quickly you are moving into the new region). If either of these things are zero, you would have zero acceleration. Commented Jan 29, 2014 at 5:18
• Mathematically, the chain rule was used.
– BMS
Commented Jan 29, 2014 at 5:37
• How was the chain rule applied? Commented Jan 29, 2014 at 5:44
• $dv/dt = dv/ds \cdot ds/dt$ is the chain rule. You can find it in the first sentence of the answer. Commented Jan 29, 2014 at 5:45