Answer Happy

QUESTION Z A horizontal platform in the shape of a circular disk rotates freely in a horizontal plane about a frictionless vertical axle as shown. The platform has a mass M 100 kg and radius R = 2 m. A student whose mass is m = 60 kg is standing at the rim. You can treat the student as a point mass. The bars of the platform have negligible mass. = m (a) Assume a constant torque is exerted by the motor to accelerate the platform from rest to 3 rad/s in 1.5 seconds. M Determine the magnitude of the torque. R (b) Find the number of revolutions made by the platform while reaching 3 rad/s. (c) If the coefficient of static friction between the student's shoes and the platform is 0.6, find the maximum linear speed that the platform can have such that the student does not slide off the platform? Draw a free-body-diagram. (d) The motor is now disconnected and the platform is left to rotate freely with a constant angular speed of 3 rad/s, then the student walks slowly from the rim towards the center. What is the angular speed of the platform when the student reaches a point 0.5 m from the center?