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!

Projectile: Find initial velocity without time

  1. Sep 11, 2010 #1

    JJBladester

    User Avatar
    Gold Member

    1. The problem statement, all variables and given/known data
    Knowing that snow is discharged at an angle of 40 degrees, determine the initial speed, v0 of the snow at A. Answer: 6.98 m/s


    2. Relevant equations

    snow%20thrower.jpg

    projectile.jpg

    3. The attempt at a solution

    I have found the x and y velocity and position formulas. Now since I don't know time, should I solve both position equations for time (t) and set them equal to each other to get my only unknown, vi? The quadratic equation for time in the y-dir seems a bit hectic. Is there an easier way to go about trying to find vi?
     
    Last edited: Sep 11, 2010
  2. jcsd
  3. Sep 11, 2010 #2

    kuruman

    User Avatar
    Homework Helper
    Gold Member

    Start with
    L = v0 t cosθ
    Δy = v0 t sinθ - (1/2) g t2

    Solve the first equation for t and replace in second equation. Solve the ensuing equation for v0.
     
  4. Sep 12, 2010 #3

    JJBladester

    User Avatar
    Gold Member

    I believe this is what you had in mind. The answer matches the professor's answer. Thanks again kuruman!

    projectile%20final.jpg
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook