If the resultant of all the external forces acting on a system of particles is zero, then from an inertial frame, one can surely say that
linear momentum of the system does not change in time
kinetic energy of the system does not change in time
angular momentum of the system does not change in time
potential energy of the system does not change in time
$A$ particle of mass $2\, kg$ located at the position $(\hat i + \hat j)$ $m$ has a velocity $2( + \hat i - \hat j + \hat k)m/s$. Its angular momentum about $z$ -axis in $kg-m^2/s$ is
A bullet of mass $10\, g$ and speed $500\, m/s$ is fired into a door and gets embedded exactly at the centre of the door. The door is $1.0\, m$ wide and weighs $12\, kg$. It is hinged at one end and rotates about a vertical axis practically without friction . The angular speed of the door just after the bullet embeds into it will be
Obtain $\tau = I\alpha $ from angular momentum of rigid body.
A $bob$ of mass $m$ attached to an inextensible string of length $l$ is suspended from a vertical support. The $bob$ rotates in a horizontal circle with an angular speed $\omega\, rad/s$ about the vertical. About the point of suspension