This is the set of homework problems. These all come from Bloomfields Student Supplement .

1.6. You're about to go on a bicycle trip through the mountains. Being ambitious, you decide to take two children along. The children sit in a trailer that you pull with your bicycle.

a. As you wait to begin your trip, you and your bicycle are motionless. What is the net force on your body?

b. You begin to bicycle into the mountains. You soon find yourself ascending a steep grade. The road rises smoothly uphill and you're traveling up it at a steady pace in a straight line. You're traveling at a constant velocity up the hill. What is the net force on your body?

c. The road rises 1 m upward for every 10 m you travel along its surface. If the children and their trailer weigh 400 N, how much uphill force must you exert on the trailer to keep it moving uphill at a constant velocity?

d. When you reach the top of the hill, your altitude has increased by 500 m. How much work did you do on the trailer and children as you pulled them up this hill? Does the amount of work you did on them depend on whether you took the long, gradually sloping road or the short, steep road? (Answer both questions.)

e. How much work must you do on the trailer and children as you pull them back down the 500-m high hill at constant velocity?

1.15. You are riding your bicycle on a north-south road and have just stopped at an intersection. Use that intersection as the reference. point for position.

a. You leave the intersection with a northward velocity of 3 m/s. After 60 s, how far are you from the intersection?

b. What is your new position?

c. You abruptly change your velocity to 3 m/s toward the south. After another 60 s, what is your position?

d. Later in the day, you stop at the same intersection. This time you leave the intersection with an acceleration of 1 m/s2 toward the north. After 10 s, what is your velocity?

e. What is your position?

f. You abruptly change your acceleration to 1 m/s2 toward the south. After another 10 s, what is your velocity?

g. What is your position?

h. A trip during which you reverse your velocity is evidently quite different from one in which you reverse your acceleration. Explain this difference.

2.3. A 100,000-kg train is traveling north along a straight, level track at a constant speed of 30 m/s (108 km/h or 67 mph).

a. As it moves forward at constant velocity, what is the net force on the train?

b. What is the train's momentum?

c. To stop the train, how much momentum must you transfer to it?

d. If you exert a 500-N southward force on the coasting train, how long will it take to stop the train?