Chapter 11, Problem 4PCE

A squirrel-proof bird feeder has a lever that closes to protect the seeds when a 0.42-kg squirrel sits on it, but not when a 0.077-kg bird perches there. (a) If the lever radius is 9.6 cm, what torques do the squirrel and the bird each exert on it? (b) The torque produced by the animal is balanced by a spring that applies a perpendicular force a distance of 3.5 cm from the axis of rotation. If the squirrel must stretch the spring 2.5 cm in order to close the lever and protect the seeds, what should be the force constant of the spring?