Question

A disc is undergoing in pure rolling on a horizontal surface, then which of the statement about angular momentum of the disc is incorrect ?

• A. Angular momentum about $A$ is conserved under any situation
• B. Angular momentum about $B$ is conserved only if surface is smooth
• C. Angular momentum about any point on the disc is conserved
• D. None of these

Answer 1

The correct option is D None of these

$ABD$ will be as

Net torque abut

cone $=0$

Since torque about cone is zero and cone itself is moving with zero acceleration

Torque on the system $=0$

So, $\frac{dL}{dt}=0$

$\Rightarrow$ $L\Rightarrow$ conserved

Angular momentum about any point on the disc is conserved option D is correct