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 (am I on drugs?)

  1. Jan 26, 2008 #1
    [SOLVED] Projectile motion (am I on drugs?)

    1. The problem statement, all variables and given/known data
    I can't believe how much time I have spent on this.

    2. Relevant equations
    Constant acceleration

    3. The attempt at a solution
    Here is the data I am using to solve for

    From x direction:
    [tex]\Delta X=V_{0x}t\Rightarrow t=\frac{30}{V_a\cos30}[/tex]

    From y direction:
    [tex]\Delta Y=V_{oy}+.5a_yt^2[/tex]
    [tex]\Rightarrow 3= V_a\sin30*(\frac{30}{V_a\cos30})-16.1[\frac{30}{V_a\cos30}]^2[/tex]

    [tex]\Rightarrow 3=30\tan30-16.1*(\frac{40}{V_a})^2[/tex]

    Which gets me a negative under the radical!
  2. jcsd
  3. Jan 26, 2008 #2
    seriously I am about to lose it. i have been over this like ten times!
  4. Jan 26, 2008 #3
    Where's the negative under the radical? 40 and [tex]V_a[/tex] are both positive, right? ...
  5. Jan 26, 2008 #4
    How'd you get that "40" under the radical, anyway?? I get 34.64 ...
  6. Jan 26, 2008 #5
    Oh wow. I better look into that drugs thing. The solution is 36.7 but I am getting 42.2. But then again, I'm on drugs. So let me check again.

    Thanks B.
  7. Jan 26, 2008 #6
    Yeah, your right Bells (mind if I call ya Bells?). I'm cooked this semester. Thanks for the help.

  8. Jan 26, 2008 #7
    Happens to the best of us ... keep at it.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook