3. + v f = +8 m/s v 0 = +2 m/s t = 3 s The wind changes the speed of a boat from 2 m/s to 8 m/s in 3 s.

4. Step 1. Draw a rough sketch. Step 2. Choose a positive direction (right). Step 3. Label given info with + and - signs. + v 1 = +8 m/s t = 4 s v 2 = +20 m/s

5. Step 4. Recall definition of average acceleration. + v 1 = +8 m/s t = 4 s v 2 = +20 m/s to the right

6. Step 1. Draw a rough sketch. + Step 2. Choose the eastward direction as positive. v i = +20 m/s v f = -5 m/s Step 3. Label given info with + and - signs. E

7. Example 4: (Continued) a = - 5 m/s 2 Acceleration is directed left, west. + v o = +20 m/s v f = -5 m/s  v = (-5 m/s) - (+20 m/s) = -25 m/s

8. In 1977 off the coast of Australia, the fastest speed by a vessel on the water was achieved. If this vessel were to undergo an average acceleration of 1.80 m/s 2, it would go from rest to its top speed in 85.6 s. What was the speed of the vessel?