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Homework Help: Ramp and Pulley

  1. Oct 21, 2009 #1
    Im studying for a test tomorrow and i'm doing a question, which someone posted the answers to on here in another topic

    i did it and got the wrong answer apparently can someone check and make sure im not messing up?

    A pulley device is used to hurl projectiles from a ramp (mk = 0.26) as illustrated in the diagram. The 5.0-kg mass is accelerated from rest at the bottom of the 4.0 m long ramp by a falling 20.0-kg mass suspended over a frictionless pulley. Just as the 5.0-kg mass reaches the top of the ramp, it detaches from the rope (neglect the mass of the rope) and becomes projected from the ramp.

    The diagram is at: https://fc.amdsb.ca/~Anca_Bogorin/S...F21C-004C4D96.8/32309_124510_30.png?src=.BMP"

    (a) Determine the acceleration of the 5.0-kg mass along the ramp. (Provide free-body diagrams for both masses.)
    (b) Determine the tension in the rope during the acceleration of the 5.0-kg mass along the ramp.
    (c) Determine the speed of projection of the 5.0-kg mass from the top of the ramp.
    (d) Determine the horizontal range of the 5.0-kg mass from the base of the ramp.

    so for a)

    Fg = 20(9.81)
    Fg = 196.21N

    [tex]\sum[/tex]Fx = ma

    Fa - Ff - Fgx = ma
    196.2 - 0.26[(5.0)(9.81)/cos(30)] - [(5.0)(9.81)/sin(30)] = 25a
    196.2 - 14.73 - 9.81/25 = a
    a = 6.87 m/s2

    The Apparent Answer is:
    Thanks :), i just wana make sure im not doing something wrong so i dont make a fatal error in my test
    Last edited by a moderator: Apr 24, 2017
  2. jcsd
  3. Oct 21, 2009 #2
    Nevermind, i know what i was doing wrong, i was drawing my triangles wrong.
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