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Homework Help: Some Questions Involving Newton's Law

  1. Nov 24, 2006 #1
    A skier starts from rest at the top of a 24 degree slope 1.3 km long. Neglecting friction, how long does it take to reach the bottom?

    At what angle should oyu tilt an air table to simulate motion on the moon's surface where g= 1/6 m/s/s?

    A block is launched up a frictionless ramp that makes an angle of 35 degrees to the horizontal. If the lbock's initial speed is 2.2 m/s, how far up the ramp does it slide?

    Would drawing a picture even help in any of these?!? I'm so lost... :uhh:
  2. jcsd
  3. Nov 24, 2006 #2
    well draw a picture and see if you can understand waht is going on in these questins...

    post your drawn pictures with your marking (Free body diagrams and such) on it
  4. Nov 24, 2006 #3
    I don't know how to post pictures on here....
    I did draw them tho...
    If I have a degree and a length, how do I turn that in to finding out time?
  5. Nov 24, 2006 #4
    Pictures would help with 1 and 3. Draw free body diagrams.

    1) To find acceleration, use trig. You know that the acceleration in the y direction is 9.8 m/s^2. Find what the acceleration must be by multiplying 9.8 m/s^2 by sin(24).

    Then u can calculate the time it takes by using the equation

    Change in distance = (Initial Velocity * change in time) + (1/2 * acceleration * change in time squared)

    3) As the block moves up the ramp, it is going to slow down. So again you want to calculate this acceleration. As in problem 1, multiply 9.8m/ s^2 (acceleration due to gravity) by sin35.

    Use the equation,

    Final velocity squared = Initial velocity squared + 2 * acceleration * Change in distance

    Note that the final velocity is zero because this is where the block will stop moving up the ramp.

    Hope this helped.
  6. Nov 24, 2006 #5
    Thanks, Ed Quanta. I hope it does. :)
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