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: Rock thrown from roof

  1. Feb 4, 2007 #1
    A rock is thrown from the roof of a building with a velocity v_0 at an angle of alpha_0 from the horizontal. The building has height h. You can ignore air resistance.

    Calculate the magnitude of the velocity of the rock just before it strikes the ground.

    2. Relevant equations
    V=V_0 + at
    X=V_0t + 1/2at^2

    3. The attempt at a solution
    The catch is that when i put the answer into the system, it told me that v_o and alpha_0 are not part of the answer. Any help is appreciated.
  2. jcsd
  3. Feb 4, 2007 #2


    User Avatar
    Staff Emeritus
    Science Advisor

    Well, there are other kinematic equations, and I presume you would need to use the height, so look into the equations involving height. Do you know what constants the answer should be expressed in?
  4. Feb 4, 2007 #3


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    Dearly Missed

    Or, don't bother about sub-equations at all!

    What is the FUNDAMENTAL equation of motion valid for ALL CLASSICAL PHYSICS PROBLEMS?
  5. Sep 22, 2009 #4
    I also need help with this.... is the equation you're talking about v = x/t?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook