Chapter 5 Answers
Questions
2. The acceleration will be largest around a sharp curve because the radius is the smallest. a = v2/r. If v is constant then if "r" goes down, the "a" goes up.
3. For this question you have to think of the normal force. The road pushing on the car. By the third law the car pushes on the road. So think normal force. This is how to think of it. In circular motion, the net force always points toward the center of the circular path the object goes around. The individual forces determine the net force. For example if there is a net force to the right it means the individual force to the right is bigger than the one to the left. We will apply this thinking to this problem
On flat ground: There is no acceleration so the normal force is equal to the weight.
Car going over the top of the hill: The net force points toward the center of the circle, in this case it is the downward direction. This means the down force (weight) is larger than the up force (normal). Or N<W
Car going between a dip: The net force points toward the center of curvature which in this case points up. This means the upward Normal force is larger than the downward force of Weigh Or N> W.
Since the weight is always the same number, this means the Normal force always adjusts to make the net force point in the correct direction.
You may be aware of this from your own personal experience. Sometimes when you go over a hill quite fast, you may get that feeling in your gut like you are in free fall. This means the normal force has decrease substantially. Or on the other hand you drive down in to a dip, you may feel yourself sink into the seat a a little further.
6. by Newton's third law, the feel the same force equal to the weight of the apple. it does not matter if the apple hangs from a tree or is falling.
11. The antenna would continue the same circular orbit it had before because it would have the same velocity as the satellite. If the satellite makes a circular orbit with that velocity, the antenna must do the same.
15. This has the same reasoning as question #3.
Solutions for Problems 1,3 7 39 43 63 11 41 45 77
