After class, Stevie travels in a straight hallway with a velocity shown in the graph at right, where $t$ is measured in minutes and $v(t)$ is measured in feet per minute. 

1. Explain what is happening when $t > 4.5$ minutes.

   Hint (a):

   Notice that the velocity is negative when $t > 4.5$.

   Answer (a):

   When velocity is negative, Stevie moves back towards his starting position.

2. Calculate the total distance Stevie traveled.

   Hint (b):

   Total distance is the area under a speed graph. Speed is the absolute value of velocity.

   Hint (b):

   A speed graph is the absolute value of a velocity graph...
   $\text{Area under a speed graph = total distance}$.
   $\text{Area under a velocity graph = displacement}$.

3. If Stevie only travels in the straight hallway, how far does he end up from his original starting place?

   Hint (c):

   Distance from starting point is known as 'displacement.'
   Displacement is the area under a velocity graph.

4. What is Stevie’s acceleration at $t = 1$?

   Hint (d):

   Acceleration is slope on a velocity graph.

5. When is Stevie’s acceleration equal to zero?

   Hint (e):

   See hint in part (d).