P Pivot FIGURE Q8.1

A uniform horizontal shelf of width L and mass m is held to a wall by a frictonless hinge and by a string at an angle of , measured from the shelf. The string is connected by the shelf at a distance of x from the wall. What is the tension in the string and what are the horizontal and vertical components of the hinge's force?

3. A person holds a 10.0 kg lead ball in his hand, a distance of 32.0 cm from the elbow joint, as shown. The biceps, attached at a distance of 2.5 cm from the elbow, exerts an upward force on the forearm. Consider the forearm and hand to be a uniform rod with a mass of 1.50 kg. Calculate the force provided by the biceps muscle in order to hold the arm horizontally as shown. Use the elbow joint as the pivot point. Biceps 32 cm 2.5 cm

You push on the door as shown in the drawing. Calculate the torque experienced at the door hinge.