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!

Change in Momentum using Vectors

  1. Jan 23, 2016 #1
    1. The problem statement, all variables and given/known data
    A force F = (2ti + 3t^2j) N acts on an object moving in the xy plane. Find the magnitude of change in momentum of the object in time interval t=0 to t=2
    (The bold ones are vectors)
    2. Relevant equations
    Ft=change in momentum

    3. The attempt at a solution
    magnitude of F = (4t^2 + 9t^4)^(1/2)
    taking t^2 common:
    t(4+9t^2)^(1/2)
    Ft=delta p
    so, delta p = 2t(4 + 9t^2 ) ^ (1/2)

    But the answer doesn't have ts in it.
     
  2. jcsd
  3. Jan 23, 2016 #2
    Have you learnt calculus? The force is time-dependent, so you will have to perform an integration to find out the total change in momentum over the time interval.
     
  4. Jan 23, 2016 #3
    I have learnt it. But have never actually used it in physics.
    So I integrate F?
    Like:
    Integration of 2ti+3t^2 j
    is t^2i + t^3j
    with the limits 0 and 2
    Then,
    4i + 8j is the change in p
     
  5. Jan 23, 2016 #4
    Yes. You can understand the integration process by looking at Newton's second law, which states that [tex]\vec{F} = \frac{d\vec{p}}{dt}[/tex], and so this immediately results in [tex]\Delta p = \int_{t_0}^{t_f}\vec{F} dt [/tex]
     
  6. Jan 23, 2016 #5
    Thank you!
     
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: Change in Momentum using Vectors
Loading...