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Homework Help: Physics - Mechanics?

  1. Sep 26, 2006 #1
    Physics - Mechanics??

    hey i got a problem

    A snowball rolls off a barn roof that slopes downward at an angle of . The edge of the roof is 14.0 m above the ground, and the snowball has a speed of 7.00 m/s as it rolls off the roof. Ignore air resistance.

    Part A
    How far from the edge of the barn does the snowball strike the ground if it doesn't strike anything else while falling?

    Part B
    A man 1.9 m tall is standing 4.0 m from the edge of the barn. Will he be hit by the snowball?
    I dont know how to get started a help would be great.
  2. jcsd
  3. Sep 27, 2006 #2


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    Solve this in 2 parts. First you have the falling body problem.

    You need to find the component of the initial velocity which contributes to the falling motion. Use that to find the time the snowball takes to reach the ground. Once you know that time you can compute the distance from the barn.
  4. Sep 27, 2006 #3
    u havent mentioned the angle
    if let us suppose angle = @
    the height of edge = y
    the distance required = x
    it is making a triangle having one side and one angle known
    neglecting velocity
    tan@ = y/x => x = y/tan@
    from that u can find out the B part also
    the solution is only mine
    so if u feel i m wrong plz tell me .......
  5. Sep 27, 2006 #4
    No, this is not correct. You have forgotten to take inti account gravitational force in the motion. The path followed will be parabolic and not a straight line.
    Follow Integral's advice.
    For part B, you had better make an eqn in x and y for the projectile by eliminating time from the two eqns for x and y.Then put x value of the man in the obtained eqn, and see if the y value is greater than or less than the man's height.
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