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!

I have a question I need help with (acceleration)

  1. Jun 25, 2004 #1
    I have a question I need help with

    I am having trouble figuring out what to do with this problem. Can anyone help?



    An automobile starts from rest and accelerates to a final velocity in two stages along a straight road.Each stage occupies the same time. In stage 1, the magnitude of the car's acceleration is 3.0 m/s^2. The magnitude of the car's velocity at the end of stage 2 is 2.5 times greater than it is at the end of stage 1. Find the magnitude of the acceleration in stage 2.
     
  2. jcsd
  3. Jun 25, 2004 #2
    2.5*(3t) = 3t + a * (t)
    7.5t - 3t = at
    4.5t = at
    a = 4.5

    wow, i hope i didn't make any mistakes.

    edit: i did lol, too late for me. such sillyness. (rechecks my stats homework)
     
    Last edited: Jun 25, 2004
  4. Jun 25, 2004 #3
    Stage one:
    V = ?, u = 0, a = 3ms^-2, t=t
    v=u+at
    ?=3t

    Velocity at end = 2.5(3t) = 7.5T

    Stage two:
    U = 3t, V = 7.5t, a = ?, t=t
    v = u + at
    7.5t = 3t + at
    divide through by t
    7.5=3+a
    a=7.5-3
    a=4.5ms^-2

    Where U = speed at the beggining of the stage, V = Final speed, T = time, a = acceleration.
    Kinematics is fun, don't be afraid to leave things as unknowns in algebraic form if you have to compile information in two stages. A lot of examination 'proof' questions will ask for this.
     
    Last edited: Jun 25, 2004
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: I have a question I need help with (acceleration)
  1. Help I need questions! (Replies: 0)

Loading...