Lesson 2
Newton's Laws

Name:etp Section:M2 Start Time:11:54:24 Instructor:pate Course:355

1) Probably all of us have heard the familiar statement, "For every action, there is an equal and opposite reaction." Is this really true? Is there an "equal and opposite reaction" for every action? Please answer in your own words (not textbook-ese).



2) Suppose you are playing ice hockey on a frozen lake. The lake is completely frozen over, so there's plenty of room for the puck to slide. You give it a good whack. Gradually, it slows down and comes to rest.

If you assume you can model the resistive force as Fresist=kmv, where k is a constant, m is the mass of the puck, and v is the speed of the puck, estimate a reasonable value for k. (Please state any assumptions you make in order to come up with this estimate.)

At what location (distance away from you) will the puck reach half of its initial maximum speed? At what approximate time will this occur? (Again, please briefly explain the procedure you follow to answer these questions.)



3) Which of the following statements is correct?

  1. Newton's Laws are valid in a rotating coordinate system.
  2. If Newton's Laws are valid in a given reference frame, that frame is not moving relative to an inertial reference frame.
  3. A free particle need not obey Newton's Laws.
  4. Newton's Laws describe motion of bodies in inertial reference frames.



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