An old wooden telephone pole with a single cross member was blown off center dur
ID: 1822375 • Letter: A
Question
An old wooden telephone pole with a single cross member was blown off center during a recent storm. To temporarily stabilize the telephone pole, a repair crew has attached a cable from the end of the cross member to an eye-ring stake anchored in the ground. (Part C figure) If the origin O of a coordinate system is placed where the pole meets the ground, the point where the cross member is attached to the pole is A(-1.50,1.90,24.8)ft and the point where the cable is attached to the end of the cross member is B(-1.50,-3.10,27.8)ft. The cable's direction is {1.00{i}-1.00{j}-1.00{k}} and it has a tension of 185lb. What is M_a, the moment that tends to twist the telephone pole due to the tension in the cable applied at point B?
Explanation / Answer
moment= r X T r is the distance between A and B. r= position vector of B- position vector of A =(0, -2.5,1.5) T=F=925*(1,-1,-1)/v3 = -534.05 so the answer would be the cross product of (534.05,-534.05,-534.05) X (0,-2.5,1.5)