Meriam, Kraige & Bolton — Kinetics of Particles: Problem 3_68

3/68 The spring-mounted 0.8-kg collar A oscillates along the horizontal rod, which is rotating at the constant angular rate \(\dot{\theta} = 6 \text{ rad/s}\). At a certain instant, \(r\) is increasing at the rate of \(800 \text{ mm/s}\). If the coefficient of kinetic friction between the collar and the rod is 0.40, calculate the friction force \(F\) exerted by the rod on the collar at this instant.