1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Angle of a projectile

  1. Sep 2, 2011 #1
    "A long jumper rises 0.5 meters during the flight phase of his jump. His forward velocity is 8 ms. What is the angle of take off?"

    Okay, I did a skectch to work out basic trig, with 8m/s as my H and 0.5m as my 0
    using sinϑ=o/h, =0.5/8 = 3
    but it should be 21.6 .... do you know where I went wrong??
  2. jcsd
  3. Sep 2, 2011 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    I see a couple of problems so far. The first is that I would interpret the 8 m/s as the horizontal component of the velocity. Therefore if you draw a right triangle consisting of the velocity vector and its two components, the 8 m/s is not the hypotenuse of the triangle, but rather the horizontal leg.

    The second problem is that you don't know what the vertical component is. You have to be careful here -- the 0.5 m provided is a distance, not a velocity. It's a little ambiguous what the "flight phase" of the jump is, but if you assume 0.5 m to be the maximum height that he reached, then you have enough info to solve the problem.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook