## Acceleration Homework

1. A girl can row a boat at a speed of 5 km/h in still water. The girl heads across a river that is 25 km wide. What is the boat's velocity in m/s? How long will it take her to cross the river? Ans: 1.39 m/s, across the river; 18,000 sec
2. If a ball is dropped and attains a velocity of 29.31 m/s in a time interval of 3 sec on another planet, what is the acceleration of gravity on this planet? Ans: 9.77 m/2, down
3. A large rock is dropped from a bridge into the river below. If the time required for it to drop is 1.7 sec, with what speed does it hit the water? Ans: 16.66 m/s
4. A runner accelerates from rest at a rate of 1.40 m/s2 over a time interval of 8 sec. What is his final velocity? How far dod he travel? Ans: 11.2 m/s, down the track; 44.8 m
5. A car traveling at 4 m/s, south, accelerates at 5 m/s2 over a displacement of 114 m, south. What is his final velocity? Ans: 34 m/s, south
6. a woman on a motorcycle moving uniformly at a rate of 60 m/s passes a truck at rest. At the instant the motorcycle passes the truck, the truck begins to accelerate at the rate of 4 m/s2. How long does it take the truck to catch up to the motorcycle? How far has the motorcycle traveled? What is the truck's speed at this point? Ans: 30 sec; 1800 m; 120 m/s
7. What is the acceleration of the object in the graph at these exact times: 2 sec, 5 sec; 7 sec, and 14 sec? Ans: zero; 1 m/s2; -0.67 m/s2; 0.67 m/s2