| Last revised 1999/10/05 |
10 & 39. The crucial point is the meaning of "on the verge of losing contact with the track." This statement tells you the value of the normal force exerted by the track at that point. Note that as you change the velocity of the block at the top of the loop, the normal force changes smoothly, not abruptly.
In part (a) of problem 39, there are both horizontal and vertical components to the force acting on the block. You need to know the velocity of the block at that point; how do you find it?
40. How is this problem related to problem 39?
44. Don't forget that gravity is still acting when the block is in contact with the spring. Watch your angles.
Part (b) has a simple answer. It is not worked using the same method used on part (a).
46. Make sure you understand this one. K(x) is largest for intermediate values of x.
49. This problem is related to # 46.
75. This one has all aspects of work and energy in it. The answer to part (c) will be easier to find if you work the first two parts symbolically, or at least keep a symbol for the mass in your algebra.