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: Newtonian stuff

  1. Jan 22, 2006 #1
    ex) you throw a baseball straght up. I returns after 3.5 sec. How fast did you throw it?

    i could then use x = x(initial) + v(initial)*3.5s + 1/2(-9.8)(3.5^2) and solve for initial velocity which comes out to be 17.5m/s.

    in this problem, 9.8 was negative and in some other problems, 9.8 was positive. how do i decide when to set 9.8 + or -?
     
  2. jcsd
  3. Jan 22, 2006 #2

    Integral

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    It depends on how you define your coordinate system for the problem. It really does not make any difference as long as you are consistent.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook