The 0.07-kg particle has a speed v = 8.6 m/s as it passes the position shown. The coefficient of kinetic friction between the particle and the vertical-plane track is μk = 0.24. Determine the magnitude of the total force exerted by the track on the particle. What is the change in speed v˙ (positive if speeds up, negative if slows down) of the particle? Answers: F = N v˙ = m/s2