Math21a, Fall 2000 Course Head: Prof. Clifford H. Taubes

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 Answers to non-text book Physics section suggested problems

 Section 1.3-1.4: 1) If the vertical vector, upward pointing unit vector is denoted by e and the unit vector in the direction of the horizontal projection of F is denoted by eŽ, then F = 12 2-1/2 (e + eŽ). 2) Let e denote the unit vector in the direction of the vertical projection of F and let eŽ denote the unit vector in that of the horizontal projection. Then, F = 5 (e + 31/2 eŽ). Sections 1.6-1.7: 1) The work is 3 as measured in the implied units. Sections 1.7-1.8: 1) The angular momentum vector is r x r = (-31/2/2, 0, 1) which is constant. This means implies that the motion is in the plane where -31/2 x/2 + z = 0. Section 5.1: 1) The work is 5/3 in the implied units. Section 2.7: 1) The minima is at p = 0 and = , the value there is ­1. Section 3.4: 1) The total mass is 1000/3. The center of mass is (0, 0, 15/4). Section 5.5 1) The total charge is 4. 2) The total charge is 4/3.

 Last update, 9/20/2000, math21a@fas.harvard.edu