10.62.Set Up:The free-body diagram for the arm is given in Figure 10.62. Take the pivot at the shoulder joint andlet counterclockwise torques be positive. Use coordinates as shown. Let Fbe the force exerted by the muscle. Thereare also the weight of the arm and forces at the shoulder joint, but none of these forces produce any torque when thearm is in this position. The forces Fand Thave been replaced by their xand ycomponents.Figure 10.62Solve:gives 10.63.Set Up:The weight on the front wheels isthe normal force exerted by the ground on the front wheels.The weight on the rear wheels isthe normal force exerted by the ground on the rear wheels. When the front wheelscome off the ground,The free-body diagram for the truck without the box is given in Figure 11.63a and withthe box in Figure 11.63b. The center of gravity of the truck, without the box is a distancexfrom the rear wheels.Figure 10.63Solve:in Figure 11.63a gives in Figure 11.63a, with the axis at the rear wheels and counterclockwise torques positive, givesand(a)in Figure 11.63b, with the axis at the rear wheels and counterclockwise torques positive, gives
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