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!

Momentum and impulse question

  1. Jan 17, 2006 #1
    A 230N force causes a 4.0kg to accelerate from 5.0m/s North to 3.0m/s east. for how much time does hte force act?

    t = m(vf-vi) / F

    i got this but the trouble is vf and vi are in different directions...and since t is not a vector i can't break it down to components. what should i do?
     
  2. jcsd
  3. Jan 17, 2006 #2
    Maybe you can do it by this way.
    let [tex] \vec{v_i} =(0,5)[/tex] [tex] \vec{v_f}=(3,0)[/tex]
    so [tex]\Delta \vec{v} =(3,-5) [/tex]
     
  4. Jan 18, 2006 #3

    Tide

    User Avatar
    Science Advisor
    Homework Helper

    You can integrate

    [tex]\frac{d\vec{v}}{dt} = \frac{\vec{F}}{m}[/tex]

    Your solution will be two equations (one for each component of velocity). You know the initial and final velocity vectors. Your unknowns are the two components of [itex]\vec F[/itex] and t but you also know

    [tex]F^2 = F_x^2 + F_y^2[/tex]

    where F = 230 N. You should be able to handle the details.
     
    Last edited: Jan 18, 2006
  5. Jan 18, 2006 #4

    andrevdh

    User Avatar
    Homework Helper

    using
    [tex]F_x\Delta t\ =\ m\Delta v_x\ =\ a[/tex]
    [tex]F_y\Delta t\ =\ m\Delta v_y\ =\ b[/tex]
    and then
    [tex]a^2\ +\ b^2\ =\ \Delta t^2 \mid F\mid^2[/tex]
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Momentum and impulse question
Loading...