Question

The wheels, axle, and handles of a wheelbarrow weigh W = 65 N. The load chamber and its contents weigh WL = 627 N. The drawing shows these two forces in two different wheelbarrow designs. To support the wheelbarrow in equilibrium, the man’s hands apply a force to the handles that is directed vertically upward. Consider a rotational axis at the point where the tire contacts the ground, directed perpendicular to the plane of the paper. Find the magnitude of the man’s force for both designs.

Answer 1

Weight of the wheelbarrow, W = 65 N

    Weight of the load, W_L = 627 N

    Case (a) :

             Underequilibrium conditions,

          CounterclockwiseTorque = Clockwise Torque

             F ( 0.4 +0.2 + 0.7 ) = W_L * 0.4 + W ( 0.4 + 0.2 )

             F * 1.3 =627 * 0.4 + 65 * 0.6

             F =223 N


    Case (b) :

             Underequilibrium conditions,

          CounterclockwiseTorque = Clockwise Torque

             F ( 0.6 +0.7 ) = W_L * 0 + W ( 0.6 )

             F * 1.3= 65 * 0.6

             F = 30 N

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