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: Kinematics Problem and final velocity

  1. Sep 10, 2004 #1
    Problem: The acceleration of a particle is given by Ax(t) = -2.00m/s^2 + (3.00m/s^2)t. A) Find the initial velocity such that the particle will have the same x-coordinate at t= 4.00s as it had at t= 0. B) What will the velocity be at t= 4.00s?

    Work so far:

    Integrated to get these:

    Vx(t) = -2t + (3/2)t^2
    x(t) = -t^2 + (1/2)t^3

    I am just stuck on what to do. I dont need it worked out as much as I just need a push in the right direction. Thanks.
  2. jcsd
  3. Sep 10, 2004 #2
    Both your equations are wrong. When you integrated the acceleration, you forgot about the constant of integration or the initial velocity.
  4. Sep 10, 2004 #3
    So then they are:

    Vx(t) = Vi + [-2t + (3/2)t^2]
    x(t) = Xi + Vi(t) + [-t^2 + (1/2)t^3]

    With Vi meaning initial velocity and Xi meaning initial position.

    I just solved it, thanks for the correction.
    Last edited: Sep 10, 2004
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook