3

3) Make-up A 20-cm radius grinding wheel having a moment of inertia of 0.80 kg.m rotates in a horizontal plane about an axis through its center. The angular velocity is 120 rpm when a damp cloth is pressed on the rim of the wheel. The wheel slows down until it stops at a constant angular deceleration of 2.1 rad/s2. a) Find the initial rotational kinetic energy of the wheel. (7 points) b) What is the mass of the wheel? (7 points) c) Find the magnitude of the friction force between the wheel and the cloth. (9 points) d) What was the tangent velocity of a point on the rim before the cloth was pressed on the rim of the wheel? (5 points) e) How long does it take to stop the wheel from rotating? (7 points) f) Through how many revolutions does the wheel turn during this time? (7 points) w V Fir