A rod is lying on the top of a table. One end of the rod is hinged to the table so that the rod can rotate freely on the tabletop. Two forces, both parallel to the tabletop, act on the rod at the same place. One force is directed perpendicular to the rod and has a magnitude of 40.5 N. The second force has a magnitude of 49.5 N and is directed at an angle θ with respect to the rod. If the sum of the torques due to the two forces is zero, what must be the angle θ?
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A flywheel is a solid disk that rotates about an axis that is perpendicular to the disk at its center. Rotating flywheels provide a means for storing energy in the form of rotational kinetic energy and are being considered as a possible alternative to batteries in electric cars. The gasoline burned in a 350-mile trip in a typical midsize car produces about 1.90 109 J of energy. How fast would a 18-kg flywheel with a radius of 0.23 m have to rotate to store this much energy? Give your answer in rev/min.