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Homework Help: Frictionless Peg Slide On Wedge

  1. Jan 12, 2009 #1
    Hey, im new but was trying to find help online and found this site...hopefully someone will be willing to help me.

    I used to be really good at mech but ive gone blank and my exams wed and i was wondering if someone could just help we with where to start even if they dont know the ans it would be helpful.

    Q: a 8kg block is inclined on a 40 degree slope connected by a light string to a 10 kg block on a 50 degree slope which passes over a frictionless peg slide on a frictionless inclines. Find the acceleration of the 8kg block and the tension in the rope.

    I really need help its a basics and ive forgot them and im really panicing.

    Sorry to bother you all

  2. jcsd
  3. Jan 12, 2009 #2


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    Science Advisor

    Do you remeber how to calculate vectors? (Gravity will pull straight down, so the angle of the inclines will give you the respective velocity vectors.)
  4. Jan 12, 2009 #3


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    Gold Member

    Yes as he said. Simply draw a diagram of the 2 blocks (don't forget tension between the 2 blocks on the rope) for starters the force sliding the blocks down the plane is mgsin[tex]\theta[/tex]

    [tex]\theta = 50 degrees[/tex] of course
  5. Jan 12, 2009 #4


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    Homework Helper

    Draw F = mg straight down. Use a right triangle to separate this F into a part along the slope and another component perpendicular to the slope.
  6. Jan 12, 2009 #5
    Thank you thank you thank you....to you all! Thats really got me mad i really was drawing a blank....I'm pretty screwed if im doing that 2 days before my 1st year exam at uni....whats year 2 and 3 ging to be like a dread to think! haha

    Cheers All! :D
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