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: Quick Projectile Question

  1. Dec 16, 2005 #1
    If two objects are fired, both from a height h and speed v0, where object A is fired at an angle θ with the horizontal and object B is fired at an angle of 2θ, which will land with a greater speed?

    It seems to me that the speed would be the same for both, although the velocity vectors would differ in their x- and y-components. Is my answer correct? The question asks to explain this without any equations, so I am having trouble justifying it. Any ideas? Thank you.
     
  2. jcsd
  3. Dec 16, 2005 #2

    Tide

    User Avatar
    Science Advisor
    Homework Helper

    HINT: Energy is conserved! :)
     
  4. Dec 16, 2005 #3
    So if I use y=0 as my reference point and y=h as the launching point, I can say that:

    Object A:

    [tex]mgh+\frac{1}{2}m{v_{0}}^{2}=\frac{1}{2}m{v_{A}}^{2}[/tex]

    Object B:

    [tex]mgh+\frac{1}{2}m{v_{0}}^{2}=\frac{1}{2}m{v_{B}}^{2}[/tex]

    Then vA must equal vB. Is this correct?
     
  5. Dec 16, 2005 #4

    Tide

    User Avatar
    Science Advisor
    Homework Helper

    Yes, and you can even say that without using equations! :)
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook