Question

What is the dot product of the components of the force vector shown in the figure, i.e. the dot product of the z-axis component and the y-axis component of the force?

(a) 0

(b) 200cos60°

(c) 200sin45°

(d) 200cos30°

I got this question in an international level competition.

My query is from Cables Subjected to a Distributed Load topic in portion Internal Forces of Engineering Mechanics

Answer 1

The correct answer is (a) 0

For explanation: The dot product of any two vectors is having the cosine function in it. It is being multiplied by the product of the magnitudes of the vectors. So if the angle is 90°, then the value of cosine function would be zero, thus 0. And the value of the sine angle is 1, thus the result.