Q. When a mass is rotating in a plane about a fixed point, its angular momentum is directed along:
A) the tangent to the orbit
B) a line perpendicular to the plane of rotation
C) the line making an angle of 45° to the plane of rotation
D) the radius
Explanation
[Solution from source] Angular momentum L = r × p, and both r and p lie in the plane of rotation, so L is perpendicular to that plane. The tangent is the direction of linear momentum, and the radius is the direction of r. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.