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!

Need help finding a derivation of the range formula

  1. Mar 26, 2008 #1
    I need to find a derivation of the range formula for a projectile in the absence of air.

    i know that the range formula is Range=Vhxt
    i know that Vh=vcostheta

    but in having trouble understanding how V=Vo+at can be re-arranged to = 2Vsintheta/g=t where a=g=9.8m/s/s (gravity)

    i know V=Vo+at can be arranged to equal V-Vo/g=t
    but this is where i get stuck, i dont know how to get to V-Vo=2Vsintheta

    i know that vsintheta = vertical velocity

    If anyone can help it would be appreciated heaps
  2. jcsd
  3. Mar 26, 2008 #2
    Because of the symmetry of the parabola, the ball will hit the ground with a vertical velocity of -Vo*sin(theta). So the net change in velocity is 2*Vo*sin(theta) which takes t=2*Vo*sin(theta)/g
    That's a pretty hand-wavy explanation though.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook