1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Finding gravitational acceleration

  1. Apr 20, 2010 #1
    1. The problem statement, all variables and given/known data
    A cannon is fired on another planet straight up at 25 m/s. It reaches a maximum height of 50m. What is the value of the gravitational acceleration?

    2. Relevant equations
    v = v_i + at
    x = .5 (v_i + vt)

    3. The attempt at a solution
    using the first equation,
    a = (v - v_i)/t
    a = (0-25)/2
    g = -12.5 m/s^2
    Where am I going wrong? Thanks
  2. jcsd
  3. Apr 20, 2010 #2


    User Avatar
    Science Advisor
    Homework Helper

    Welcome to PF!

    Hi BTurner90! Welcome to PF! :smile:

    (try using the X2 tag just above the Reply box :wink:)
    There are three standard constant acceleration equations, so choose the one that only has what you already know, and what you want to know.

    In this case, you don't have t, and nobody's asking you for it, so choose an equation with u v a and s. :wink:
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook