Torques on a Disk A drum of radius R = 0.450 m, mass M = 22.5 kg and length L =
ID: 2092315 • Letter: T
Question
Torques on a Disk A drum of radius R = 0.450 m, mass M = 22.5 kg and length L = 2.25 m rotates on axle A that lies on the axis of symmetry for the drum. With the origin at the center of the drum, two constant forces act on it, F1 = 275 N at angle 135 at the point (R,0) , and F2 = 115 N at angle 225 at the point (0,-R / 2) . What third force, F3 = X acting horizontally at (0,R) is needed to ensure the drum will not rotate.Explanation / Answer
FOLLOW THIS SOLVED EXAMPLE Find the resultant of 1 & 2 in the +X & +Y direction =>R(+X) = F2 - F1sin30* = 14.8 - 20.8 x 0.5 = 14.8 - 10.4 = 4.4 N =>R(+Y) = F1cos30* = 20.8 x 0.87 = 18.1 N Let the third force F3 is acting at an angle A* from -X axis towards -Y axis =>F3sinA* = R(+Y) = 18.1----------------------------(i) =>F3cosA* = R(+X) = 4.4 ----------------------------(ii) By (i)^2 + (ii)^2 :- =>F3 = sqrt[(18.1)^2 + (4.4)^2] = 18.63 N By (i)/(ii) :- =>tanA* = 18.1/4.4 = 4.11 = tan76.4 =>A* = 76*4'