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HINT: (VECTOR ADDITION) THE AXIS OF ROTATION PASSES THROUGH theta. FIGURE-3 Figu

ID: 1816736 • Letter: H

Question

HINT: (VECTOR ADDITION) THE AXIS OF ROTATION PASSES THROUGH theta. FIGURE-3 Figure 3 shows three forces acting on a pipe assembly that can rotate through an axis passing through the origin. Distances are in meters and forces are in Newton, Two forces are coming out of the paper and one force is going into the paper as indicated. The position vector for each force is measured with respect to the origin. The Z axis is perpendicular to the paper passing through the origin. Find the individual moments and the net moment. Remember that we are dealing here with vector quantities. Hint: Notice the position of the X and Y axis. The Z axis is perpendicular to the paper. Make sure you get the i. j and k unit vectors in the correct directions.

Explanation / Answer

position vector of F1 = -1.25i
force F1 = 180k

torque produced by F1 = (-1.25i) X (180k)
= 225j

position vector of F2 = -1.25i + 0.5j
force F2 = 20k

torque produced by F2 = (-1.25i +0.5j) X (20k)
= 25j + 10i

position vector of F3 = -2i + 0.5j
force F3 = -150k

torque produced by F3 = (-2i +0.5j) X (-150k)
= -300j -75i

net torque = torque1+torque2+ torque3

   = 225j+25j+10i-300j-75i

   = 250j-300j-65i

   = -50j-65i

   = -(65i+50j)