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: Movement in x,y line

  1. Sep 6, 2012 #1
    1. The problem statement, all variables and given/known data
    From a height 40 meters up, one throw a ball with the velocity of 20 m/s. The elevation is 0°. How far does the ball come?

    vo = 20 m/s
    x = 40 meters
    α = 0°

    2. Relevant equations

    y = v0 × t × sinα - (9.82×t2)/2

    x= v0×t×cosα

    3. The attempt at a solution
    I put what I know in there

    40 = 20×t×sin0° - (9.82×t2)/2
    80/9.82 = t2
    √(80/9.82) = t = 2.85 s (Is that right?)

    Then I put all I know in the other formula to get x:
    x= v0×t×cosα

    x = 20×2.85×cos0°
    x=57 meters
    (Doesn't that feel a little too short?)

    I've no answer to this question and I would be really glad if someone could confirm that this is correct calculated :)
    Edit: There's no air resistance
  2. jcsd
  3. Sep 6, 2012 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Looks good to me.
  4. Sep 6, 2012 #3
    I hope so. Thanks for checkin' it :)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook