Question

A uniform disk with mass m = 8.55 kg and radius R = 1.35 m lies in the xy plane and centered at the origin. Three forces act on the disk in the +y-direction (see figure below): (1) a force F1 = 335 N at the edge of the disk on the +x-axis, (2) a force F2 = 335 N at the edge of the disk on the ?y-axis, and (3) a force F3 = 335 N at the edge of the disk at an angle ? = 30o above the ?x-axis. Figure 2: Problem 2. (a) What is the magnitude of the torque on the disk about the z axis due to F1? (1pt) (b) What is the magnitude of the torque on the disk about the z axis due to F2? (1pt) (c) What is the magnitude of the torque on the disk about the z axis due to F3? (1pt) (d) What is the magnitude and direction (clockwise or counterclockwise) of the angular acceleration about the z-axis of the disk? (2pt) (e) If the disk starts from rest, what is the rotational energy of the disk after the forces have been applied for t = 1.6 s? (2pt) (f) What is the linear acceleration and velocity of a point on the rim of the disk at that time? (2pt) (g) How many revolutions does the disk make during those 1.6 s? (1pt)

Answer 1

Given that A uniform disk with mass m = 8.55 kg and Radius R = 1.35 m lies in the xy plane Magnitude of torque = f_1 times r Magnitude of torque = 335 times 135 = 452.25 Nm for f_2 Magnitude of torque = F_2 .0 = 0 Nm sue to F_3 Magnitude of torque = F_3 times r times sin(30) = 226.125 nm x - component of magnitude of net torque = 0Nm \r\n y - component of magnitude of at torque T_2 = T_1 - t_3 226.125 Nm