a 4.0m long, 500kg steel beam extends horizontally from thepoint where it has been bolted to the framework of a newbuilding under construction. a 70kg construction worker standsabout the point where the beam is bolted into place? the answer is 12.5kNm, but I got a weird answer... a 4.0m long, 500kg steel beam extends horizontally from thepoint where it has been bolted to the framework of a newbuilding under construction. a 70kg construction worker standsabout the point where the beam is bolted into place? the answer is 12.5kNm, but I got a weird answer...
Explanation / Answer
Given that thelength of rod is L = 4.0 m Mass of rod is M =500 kg mass of person is m= 70 kg -------------------------------------------------------------------- Let the person stands at the end of rod that is Lmeters from the pivot. Since the mass of the beam acts at the center of massof the rod. Then the torque about the pivot is = Mg*L/2 + mg*L =( M*L/2 + mL )g = ( 500kg *2.0m + 70 kg *4.0m )(9.8m/s2) =12.5 k N.m