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: Projectile Motion diver leap

  1. Nov 25, 2008 #1
    1. The problem statement, all variables and given/known data
    A diver leaps from the top of a tower with an initial horizontal velocity of 5.0 m/s and an upward velocity of 2.0 m/s. Use a vector diagram to indicate the diver's horizontal and vertical velocity components 1.0s after he leaves the tower.

    2. Relevant equations
    y= vyt + 1/2gt2
    maybe v=d/t

    3. The attempt at a solution

    I'm not exactly sure how to go about this problem. Do I just use the x and y formula, and that is all?
    Vx= x/t

    Vy= (y-1/2gt2)/t

    Would those be right?
  2. jcsd
  3. Nov 26, 2008 #2
    Not quite right. The best equation to use here is v2 - v1 = a(t2 - t1). So for vx, a =0 and v2 = v1 = 5. (as you said). For vy, a = -9.8 and v2 = 2 - 9.8 = -7.8.
  4. Nov 26, 2008 #3
    Really? They haven't mentioned that formula in what I've done so far...
  5. Nov 27, 2008 #4


    User Avatar
    Homework Helper

    I had never witnessed such a formula either till it clicked - it's just a slight modification to the [tex]v=u+at[/tex] formula.
    v = final velocity
    u = initial velocity
    a = acceleration due to gravity
    t = time

    And yes, this is the best formula to use in this case. Horizontal velocity will be kept constant at 5ms-1 since we are assuming no resistances, so you already know what that vector is going to be after 1 second. Now you just need to calculate the vertical vector with this equation, which ak1948 already gave as -7.8ms-1.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook