The bar A of mass m is formed into a 90° circular arc of radius r and is attached to t...

The bar A of mass m is formed into a 90° circular arc of radius r and is attached to the hub by the light rods. The curved bar oscillates about the vertical axis under the action of a torsional spring B. At the instant under consideration, the angular velocity is and the angular acceleration is α. Write expressions for the moment M exerted by the spring on the hub and the horizontal force R exerted by the shaft on the hub.