Question

In an orbital motion, the angular momentum vector is

• A. along the radius vector
• B. parallel to the linear momentum
• C. in the orbital plane
• D. perpendicular to the orbital plane

Hint:

Angular momentum is the cross product of a radial vector and linear momentum vector.

Answer 1

The Correct Option is D

If a body is rotating about a given axis, then the sum of the moments of the linear momentum of all the particles is known as the angular momentum of the body about that axis. 

\[J=I \omega=m r v\]

Since the direction of velocity is perpendicular to the orbital plane \(J \propto v\), hence, in an orbital motion, the angular momentum vector is perpendicular to the orbital plane.

Answer 2

The correct option is D, perpendicular to the orbital plane.

Orbital motion is a rotational motion of a body around another one. After an orbital period, the body traces its path again. Angular momentum is the cross product of a radial vector and linear momentum vector.

Angular momentum is a vector quantity having a direction perpendicular to the plane of revolution. 

\(\overrightarrow{L} = I\overrightarrow{W}\)

\(\overrightarrow{L} \parallel \overrightarrow{W}\)

Hence, angular momentum is perpendicular to the plane of revolution.