Suppose that an object moves along an $s$-axis so that its location is given by $s(t) = t^{2}+3t$ at time $t$. (Here $s$ is in meters and $t$ is in seconds.)

(a) Find the average velocity of the object in meters per second over the time interval $t=2$ to $t=7$ seconds.

Average velocity = m/s.

(b) Find the instantaneous velocity of the object in meters per second at $t = 6$ seconds.

Instantaneous velocity = m/s.