Question

In the calculations of the bearings, we often use vector math. So for those systems which of the following is true?

(a) i x i =1

(b) j x i = -j

(c) k x j = -i

(d) k x k = 1

The question was asked during an interview.

My question is based upon Frictional Forces on Collar Bearing, Pivot Bearings and Disks in chapter Friction of Engineering Mechanics

Answer 1

The correct choice is (c) k x j = -i

For explanation I would say: As the mathematic equation for the cross product is having a cosine function in it, in which the angle used in the function is the angle between the vectors. Thus the cross product will be zero if the angle between them is 90. The vector math system remains the same for every system in the environment.