Question

In the free body diagrams involving the wedges we have use of vector math, so for two vectors A and B, what is A.B (if they have angle α between them)?

(a) |A||B| cosα

(b) |A||B|

(c) √(|A||B|) cosα

(d) |A||B| sinα

I had been asked this question during an interview for a job.

I would like to ask this question from Wedges in section Friction of Engineering Mechanics

Answer 1

Correct answer is (a) |A||B| cosα

The best I can explain: The dot product of the two vectors is always the product of the magnitudes of the two forces and the cosine of the angle between them. We need to consider the triangle and then accordingly apply the trigonometry. This is one of the ways of resolving the components.