| Last revised 1999/12/03 |
#21. "How much does X weigh?" means "How large is the gravitational force on X?"
#23. The problem essentially tells you what to do.
The result of this problem holds also if the density is the average density of a spherically-symmetric planet. In practice, however, a planet spinning this fast would be neither spherical nor spherically symmetric, but would have an equatorial radius much larger than its polar radius. A careful analysis of the maximum possible rotation rate of a planet would take distortion of the planet into account.
#53. The problem contains a hint, but even so it is not easy. Note that in the frame of reference in which the masses are at rest at the beginning, the velocity of the two masses are never the same again unless m = M.
#80. Neglect the speed of rotation of the Earth. The problem is much simpler if you use symbols!
#19. Just keep track of what mass is attached to the spring when.
#26. At what point in SHM [simple harmonic motion] is the acceleration greatest?
#51. Part (c) is what earned the "*". Don't use forces and torques, follow the hint in the problem.
#71. There is an unknown force exerted on the stick at point O. How can you tackle this problem without having to determine this force? Use the small angle approximation, sin(theta) = tan(theta) = theta for small theta.