READING QUIZ The moment of a force about a specified axis can be determined using ___. A) a scalar analysis only B) a vector analysis only C) either a scalar or vector analysis D) None of the above.

y READING QUIZ In the sketch, if u a represents the unit vector along line AB, the moment of force F about line AB, expressed in the Cartesian vector form, can be obtained using the formula M a = __________. A) (u a  r ) · F B) u a · ( r  F ) C) u a · ( r  F )  u a D) u a · ( r  F ) · u a z B x A uaua A r F

If the line of action of force F is parallel to any specified axis a-a, the magnitude of the moment of F about axis a-a is __. A) zero B) at a maximum C) the force multiplied by the shortest distance from the force line of action to the axis D) None of the above. CONCEPT QUIZ

The moment of force F about line AB is A) 300 in·lb B) 400 in·lb C) 0 D) None of the above. y 6´´ 4´´ 3´´ z B x A F=100 lb

ATTENTION QUIZ If the moment of a force about a point A is M A = {10 i + 2 j } N-m, its moment about line AB, whose unit vector is U AB = 0.6 i k, has a magnitude of ___. A) –1.6 N-m B) 1.2 N-m C) 6 N-m D) -8 N-m

1'' 3'' 2'' y x z F = 10 lb The moments of force F about the x, y, and z axes are ___, respectively. A) (20, 0, 0) in · lb B) (20, 0, 30) in · lb C) (10, 20, 0) in · lb D) (10, 20, 30) in · lb ATTENTION QUIZ