The spring-mounted 0.8-kg collar A oscillates along the horizontal rod, which is rotatin...

The spring-mounted 0.8-kg collar A oscillates along the horizontal rod, which is rotating at the constant angular rate At a certain instant, r is increasing at the rate of 800 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.