1. The problem statement, all variables and given/known data The position of an object along a straight tunnel as a function of time is plotted below: 1. Are there any time intervals in which the object has a negative acceleration? If so, list them and explain how you know. 2. Calculate the instantaneous velocity at t=20s and t-45s. 2. Relevant equations N/A 3. The attempt at a solution So, for the first question I stated that at 30s to 37s the object's velocity is decreasing, thus the acceleration is negative. However, I was told that this is only part of the interval. What am I missing? For the second question I did the following calculations: at 20s = (6 m)/(20s) = 0.3 m/s at 45s = (16m)/(45s) = 0.36 m/s I did get the instantaneous velocity at 20s correct but not the instantaneous velocity at 45 s. Where am I going wrong? Thanks for your assistance.