Question

**I have the answers for 1a and 1b but I am stuck on 2a. and 2b.**

An object is moving in a straight line according to s(t) = -t^2+4t-3 where s(t) = distance the object goes in miles at. t=times in hours
a. How far did the object go in 2 hours? Answer =4 miles
b. How fast was the object in 3 hours? Answer =-2mi/hr

*The part I need help with*
2a. What was the acceleration at 3 hrs?
2b. When was the object farthest away? How far?

Answer 1

a = -2, so constant
max s when v=0