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Homework Help: Velocity of a box going up an inclined plane.

  1. Jun 7, 2012 #1
    1. The problem statement, all variables and given/known data

    A box is hurled up an incline plane of 20 degrees at 10m/second. There is no friction. What is the velocity after 3 seconds. I know gravity and the sin of 20 degrees has to be factored in.

    2. Relevant equations

    v=u+at. u is initial velocity, v is velocity after 3 seconds, t is time.

    3. The attempt at a solution 9.81x.342=3.355ms^-2. Using the above equation I calculate -.065m/s (10-3.55x3). This does not match any of my answers. I do not know were I went off-track.
  2. jcsd
  3. Jun 7, 2012 #2
    Welcome to Physics Forums, Berean7.

    I agree with your acceleration. I see that (10-3.55x3) is u+at, but were did that
    -0.65 m/s come from?
  4. Jun 7, 2012 #3
    Check out the two numbers 3.355 and 3.55 in your analysis.

  5. Jun 7, 2012 #4
    Good catch, Chet.

    I should know better than to answer questions after hours of grading final exams...
  6. Jun 8, 2012 #5
    Thank you 4 the replies. .355 should have been used in both spots. I just typed it wrong. I arrived at the right answer.
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