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Homework Help: Tangential Forces

  1. Nov 4, 2007 #1
    1. The problem statement, all variables and given/known data

    The carbide tips of the cutting teeth of a circular saw are 8.6cm from the axis of rotation.

    The no-load speed of the saw, when it is not cutting anything, is 4800 rev/min. Why is its no-load power output negligible?

    While the saw is cutting lumber, its angular speed slows to 2400rev/min and the power output is 1.9hp. What is the tangential force that the wood exerts on the carbide tips?

    3. The attempt at a solution

    Would part a be that it's like that because it's not producing any work, there is no friction or any force acting/slowing down the rev/min.?

    How do I start part b?

    Before: 4800 rev/min 0hp
    After 2400 rev/min 1.9hp

    How would I calculate the tangential forces.?

    Please and thank you.
  2. jcsd
  3. Nov 4, 2007 #2


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    Staff Emeritus
    Science Advisor

    Well, at constant speed, it is accelerating, i.e. there is not angular acceleration.

    See - http://hyperphysics.phy-astr.gsu.edu/hbase/mi.html - for equations of rotational motion.

    See the relationship between torque, angular velocity and power. For relationship between applied force on moment arm and torque, see -

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