Q.

An object of mass 'm' is projected from origin in a vertical xy-plane at an angle 45° with the x-axis with an initial velocity v0. The magnitude and direction of the angular momentum of the object with respect to origin, when it reaches at the maximum height, will be [g is acceleration due to gravity]         [2025]

1 mv0322g along negative z-axis  
2 mv0322g along positive z-axis  
3 mv0342g along positive z-axis  
4 mv0342g along negative z-axis  

Ans.

(4)

At highest point

The speed is vx=v0cos 45°  vx=v02

H=(v02)22g=v024g

So, angular momentum about origin is

L=mvx·H

 L=m×v02×v024g

 L=mv0342g     (along negative z-axis)