A dog runs down his driveway with an initial speed of 5 m/s for 8 s, and then uniformly increases his speed to 10 m/s in 5 s.

A) what was his acceleration during the 2nd part of the motion?

B) how long is the driveway

Acceleration is given by change in velocity divided by change in time, so his acceleration should just be (10-5) / 5 which is [tex] / frac{5}{2} / frac{m}{s^{2}} [tex]

The driveway is 40 meters plus 225/4. You can do the math.