Please write your homework neatly. Don't try to cram all the problems into the
minimum space. Show your work clearly, and useful diagrams are always appropriate
and may get extra points. You may work with others, but the work should be your
own. I expect numeric answers to have a reasonable number of significant figures
and proper units.
Note: WebAssign grades only on the answer; I will grade only (mostly) on the
method! Make your method clear.
1. (a) Is there any connection between Newton’s first law and the
conservation–of–momentum law for a single particle? Explain.
(b) When a ball rolls down an incline, its linear momentum increases. Does this
imply that momentum is not conserved? Explain. [ans: Yes]
(c) A sharpshooter fires a rifle while standing with the butt of the gun against
his shoulder. If the forward momentum of the bullet is the same as the backward
momentum of the gun, why isn't it as dangerous to be hit by the gun as by the
bullet?
2. A 4–Mg truck going straight north at 24 m/s makes a 90² right turn, keeping its speed constant. What is the change in its momentum (magnitude and direction)?
3. Cummings et al., Ch. 7, p. 205, Problem 74
| 4. Find the coordinates of the center of mass for the system of two rods. The vertical rod is 4.0 cm long and has a mass of 60 grams, the horizontal rod is 6.0 cm long and has a mass of 80 grams. The rods meet at the origin. | |
5. A cylindrical rod has a variable density (mass/volume),
, where A is a constant. The rod has a length L and a radius R. ONLY the
following symbols (and maybe not all three) should appear in the answer:
A, L, R. (a) What are the SI units of the constant A? (b) Determine the total mass of the rod. (c) Determine the location of the center of mass of the rod. |
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This page maintained by Anne G. Young. Last modified 15-Oct-2004 .