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Homework Help: Static Equilibrium and frictionless inclined plane

  1. May 27, 2004 #1
    there is an object suspended on a frictionless inclined plane by a rope parallel to the incline. (the tension in the rope is 5000N). The angle on the incline is 25. I need help to find the weight of the object, I've tried everything! Thanks.
  2. jcsd
  3. May 27, 2004 #2


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    The object is in static equilibrium, so it's not moving and the net force on it is zero. The forces acting on it are the force of gravity, the tension force, and the normal force. The normal force is perpendicular to the tension force, so the normal force doesn't do anything in terms of balancing out the tension force. So what balances out the tensio force? The gravitational force. Now, you can resolve the graviational force (which is in the down direction) into two components: one angled parallel to the plane, and one angled perpendicular to the plane. The one perpendicular to the plane will balance the normal force, and the one parallel to the plane will balance the tension force. Basically, with a bit of trigonometry, knowing the angle of incline and the down-the-plane component of the force of gravity, you can find the overall force of gravity, i.e. the weight of the object.
  4. May 27, 2004 #3


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    Look up free-body diagrams and resolution of vectors in rectangular co-ordinates. I'm sure your physics text deals with these concepts.
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