46. I will post a hint when I get a question that suggests one.
47. You will want to set up your flux calculation with the origin of coordinates at the center of the loop. The distance of each point from the wire is then r + integration variable. Don't take anything out of the integral which varies as the integration variable changes. When you are done, make sure you understand why I suggested this choice of coordinates.
48.
1. The force on the rod in parts (b) to (d) is not constant.
2. Terminal velocity means that a -> 0 as t gets large
3. You don't actually have to solve a differential equation
to solve this problem. However, if you want to, see hint 4.
4. The most general solution to a linear, first-order
differential equation is B + C exp (at), and two of those constants
must be determined from the equation. Note that a differential
equation must be valid for *all* times, including t=0, t=infinity,
and everything in between.
49. This problem does have "adequate symmetry," so drawing a useful diagram is the most important part of the solution.
| Last revised 4/18/97 |