Question

a particle moves in a circukar path with decreasing speed .how does the direction of angular momentum remain constant?

Answer 1

Angular momentum of a particle is given by
L = mvr
Since speed of the particle decreases so, its angular momentum also decreases.
The direction of angular momentum of a particle or rigid body is constant in the case of rectilinear motion (pure translation). For circular motion ​its direction is perpendicular to the plane of its circular motion. (​Using the right hand rule, the direction of both angular velocity and angular momentum is defined as the direction in which the thumb of our right hand points when we curl our fingers in the direction of rotation.)