1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    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!

Interesting angle of elevation problem

  1. Oct 18, 2012 #1
    1. The problem statement, all variables and given/known data
    What is the angle of elevation of a projectile that travels THREE time horizontally its MAXIMUM height, on earth

    g = 9.800m/s2

    2. Relevant equations

    Equation 1 - H = ((vsinθ)2)/2g

    Equation 2 - R = 2v2((sinθcosθ)2/g

    3. The attempt at a solution

    I tried making 3x(equation 1)=equation 2, and letting v=5m/s, and then solving for θ, but I don't think I rearranged the equation properly. THE ANSWER IS FOR SURE 53.13°, I JUST HAVE TO SHOW HOW TO GET IT
    Thanks for any help
    Last edited: Oct 18, 2012
  2. jcsd
  3. Oct 18, 2012 #2


    User Avatar
    Gold Member

    Equation for range is not right.
  4. Oct 18, 2012 #3
    What is the equation for range? And could you help me with it?
  5. Oct 18, 2012 #4


    User Avatar
    Gold Member

    R = 2v2sinθcosθ/g. That should get you going.
  6. Oct 18, 2012 #5
    i still can't figure it out
  7. Oct 18, 2012 #6


    User Avatar
    Gold Member

    Nothing wrong with your original approach (3H = R). Show your work so you can more specifically show where you are having a problem.
  8. Oct 18, 2012 #7
    I dont need help with that one anymore, but if you could help me with a different problem, it would be great.

    a)To what elevation must one go to decrease your "weight" to one sixteenth (1/16) of its "surface" value?

    b) At the elevation calculated in part a), what is the period of this orbit?

    G = 6.670x10^-11
    R(earth) = 6.380x10^6
    M(earth) = 5.98x10^24
  9. Oct 18, 2012 #8


    User Avatar
    Gold Member

    You should start a new thread, following the template, listing all relevant equations, showing your work, etc.
  10. Oct 18, 2012 #9
    thats all i have, i have no idea how to solve it
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Interesting angle of elevation problem
  1. Angle of elevation (Replies: 1)

  2. Elevator Problem (Replies: 5)