1. Not finding help here? Sign up for a free 30min 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!

Projectile Motion range equation

  1. Sep 23, 2015 #1
    1. The problem statement, all variables and given/known data
    Uploaded
    2. Relevant equations
    x(t)=xo+v0xT+1/2axt^2
    3. The attempt at a solution
    (2Vo)costheta(t)=R, How would I get rid of T?
     

    Attached Files:

  2. jcsd
  3. Sep 23, 2015 #2

    gneill

    User Avatar

    Staff: Mentor

    Can you show how you arrived at your solution attempt? What does "costheta(t)" represent?
     
  4. Sep 23, 2015 #3
    Velocity Intial of x is equal to vocostheta, should I be using range =(vo^2sin2(theta))/gravity. I'm really lost right now...
     
  5. Sep 23, 2015 #4

    gneill

    User Avatar

    Staff: Mentor

    Okay, that's a bit better. The Range equation is a good approach. You should place the entire argument of a function within the parentheses to make it clear what the function argument is. Thus:

    R = (vo2/g) sin(2θ)

    (Note that you can use the ##x_2## and ##x^2## icons in the edit panel header to invoke superscripts and subscripts, and greek letters and other symbols can be selected from the ##\Sigma## icon's menu)

    The range equation gives you the range of a projectile that's launched with a given velocity ##v_o## at a given angle ##\theta##. So what happens to the range if you double the launch velocity?

    For the second part of the question, take a browse though your table of trig identities then ponder what happens to sin and cos if the angle is adjusted as specified in the question.
     
  6. Sep 23, 2015 #5
    Would it be 2R since the velocity is doubled?
     
  7. Sep 23, 2015 #6

    gneill

    User Avatar

    Staff: Mentor

    Can you justify that with an argument based upon the range equation? I won't confirm or deny a guess...
     
  8. Sep 23, 2015 #7
    I plugged 10 for the in initial velocity so doubling that would make 20/g therefore the outcome would be twice as great. Right logic or I'm I completely off/
     
  9. Sep 23, 2015 #8

    gneill

    User Avatar

    Staff: Mentor

    It is not correct. Does the range equation use ##v_o## or ##v_o^2##? How does squaring a doubled value affect the net result?
     
  10. Sep 23, 2015 #9
    ohhhhhhh would it be 4R cause by doubling 1 you get 2 and 2^2 is 4 so in this case quadruplicating the R.
     
  11. Sep 23, 2015 #10

    gneill

    User Avatar

    Staff: Mentor

    Bingo! It always pays to consider the equation involved and not rely on instinct alone :smile:
     
  12. Sep 23, 2015 #11
    Thank you so much it makes so much more sense now :) Would you be up to help with the rest of homework when I get stuck?
     
  13. Sep 23, 2015 #12
    For the second part would the angle be greater causing the distance to decrease? If I plug 30 in for theta, sin(90-30), the angle is greater than the previous 30, but if I plug 85 for theta the answer would less than...
     
  14. Sep 23, 2015 #13
    Nevermind, sin(90-theta) is cos
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Projectile Motion range equation
Loading...