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: Projectiles launched at an angle not sure if i posted this already?

  1. Dec 16, 2008 #1
    1. The problem statement, all variables and given/known data

    A diver pushes off horizontally from a cliff 35 m above the water, and they must clear rocks that extend 5 m from the base of the cliff. (a)What minimum pushoff speed is necessary to clear the rocks? (b)How long are they in the air?

    2. Relevant equations

    for (b) t=square root of 35/4.9=2.67 s I understand how to derive the time equation.
    for (b) y=v(y direction)t+1/2at^2 x=v(x direction)t

    3. The attempt at a solution

    I solved time already, and I got 1.85 m/s for the initial velocity in the x direction, but I cant get the correct initial velocity in the y direction. Im not even sure what Im doing wrong but its frustrating.
  2. jcsd
  3. Dec 16, 2008 #2
    thats actually not projectiles launched at an angle its horizontal projectile motion sorry-I was looking at an angled problem also, which I could use help with too.
  4. Dec 16, 2008 #3


    User Avatar
    Homework Helper

    The initial y velocity is "given" in the problem. It is zero, since he pushes off horizontally.
  5. Dec 16, 2008 #4
    Oh ok, so I dont even have to solve for that. So the answer is really the initial velocity in the x direction? 1.85 m/s?
  6. Dec 16, 2008 #5


    User Avatar
    Homework Helper

  7. Dec 16, 2008 #6
    Ok thanks!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook