Friction on the concrete surface creates a couple moment of M_O=100 N•m on the blades of the trowel. Determine the magnitude of the couple forces so that the resultant couple moment on the trowel is zero. The forces lie in the horizontal plane and act perpendicular to the handle of the trowel.
Image from: Hibbeler, R. C., S. C. Fan, Kai Beng. Yap, and Peter Schiavone. Statics: Mechanics for Engineers. Singapore: Pearson, 2013.
Solution:
The moment created by force F about the vertical axis can be written as follows:
M_C=0.75F
(Note 750 mm = 0.75 m)
As the resultant couple moment on the trowel is to be zero, we can write:
0=100-0.75F
F=133.3 N
F=133.3 N