1. The problem statement, all variables and given/known data A car's velocity can be described by v=6-0.3s. Find its acceleration at t=100s 2. Relevant equations v=ds/dt, a=dv/dt 3. The attempt at a solution This was actually a two part question, where the first part required you to find s at t=100. So I wrote: ds/dt = 6-0.3s and integrated that equation to get: s=(e-0.3t-6)/(-0.3) From which I found that at t=100s, s=20m For the second part, a=dv/dt=(dv/ds)*v To find dv/ds term, I took the derivative of v=6-0.3s and got v'=-0.3. I put the known formulas into the equation above to get: a=-0.3(6-0.3s) I know that at t=100s s=20, so I can find the acceleration at t=100 (equivalent to s=20): a=-0.3(6-0.3*20)=0 I think my thought process makes sense (it usually does), but I might be doing something stupid and not realizing it. Long story short, I just don't like a=0. However, I know some people got 0 as well and some actually got a number (this was on a midterm). Is it right? And if not, can you please point out the area where I'm doing something wrong?