Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Vector Scalar Product and KE questions

  1. Jun 13, 2006 #1
    Just a few questions from this set I have to do, I missed the class on these topics so I'm just a little confused with these last few problems.

    http://img161.imageshack.us/img161/2307/problem43eu.png [Broken]

    Concerning sets 38-39, and 40-41, I've grasped how to scalar multiply these vectors, but not how to find the angle it seems, wondering if anybody can check those out. as for the last set, i was able to find the first answer with k=.5*m*v^2, but I'm not sure what the second question is asking. I missed the class on these topics (accelerated physics in the summer, awfully bad to miss a class). thanks in advance!
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Jun 13, 2006 #2
    I believe the formula you need to use is something like:

    cos(theta) = (a * b)/(|a||b|)

    Where * is the dot product of a and b.
  4. Jun 13, 2006 #3
    aye, i wroked those angles out, inverse cosine.
    edit: i've figured out all the problems, thanks for the help everyone.
    Last edited: Jun 13, 2006
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook