10/4/10

Post date: Oct 04, 2010 12:39:45 PM

• • Bell Ringer: Two forces, one a 45N force at 35 degrees, the other a 60N force at 135 degrees, act on an object. If the object has a mass of 3.50 kg, find its acceleration.

  • Equilibrium

    • An object in equilibrium is not accelerating

    • Fnet = 0, or resultant force is zero

    • Object is moving at a constant velocity (possibly a constant velocity of zero)

    • Procedure:

      • Resolve known forces into their x and y components

      • Solve for unknown components using Rx=0 and Ry=0 (F1x + F2x + F3x +... = 0, F1y + F2y + F3y +... = 0)

      • Combine X and Y components to find magnitude and direction of unknown force.

    • Equilibrant: a single force that, when added to an object which is not in equilibrium, will put it into equilibrium

      • Equilibrant is same magnitude, opposite direction as resultant force

      • F1x + F2x + F3x +... + Ex = 0, F1y + F2y + F3y +... + Ey = 0

  • P.123: 17-21