16. Angular Momentum

Two stars are observed from Earth to be separated by a distance $d$ on the sky, and they are both at a distance $D$ from Earth. What is the angular separation $\theta$ between the two stars in degrees?

The angular momentum of a particle is ____ its velocity $v$.

A solid disk of mass $m$ and radius $R$ is rotating about its central axis. At what angular velocity $\omega$ will its angular momentum be equal to $L$?

Two ladybugs, $A$ and $B$, are sitting at different distances from the center of a rotating turntable that spins at a constant rate. If both ladybugs are fixed to the turntable, how does the angular velocity of ladybug $A$ compare to that of ladybug $B$?

A solid disk of mass $m$ and radius $R$ rotates with angular velocity $\omega$ about its central axle. What is the angular momentum of the disk about the axle?

A uniform bar of mass $m$ and length $L$ rotates with angular velocity $\omega$ about an axle passing through one end and perpendicular to its length. What is the angular momentum of the bar about the axle?

Which physical principle best explains why already spinning nebula clumps flatten into discs during their evolution?

A wheel initially at rest is subjected to a constant net torque, causing it to accelerate with a constant angular acceleration of $2.0 \mathrm{rad}/s^2$. What is the angular velocity of the wheel at $15 s$?

Which of the following refers to the angle that is rotated in a given unit of time?

A 2.00-kg rock has a horizontal velocity of magnitude 12.0 m/s when it is at point P in Fig. E10.35. At this instant, what are the magnitude and direction of its angular momentum relative to point O?

Why does the Sun rotate differently than solid objects such as a spinning disk or a wheel?

A salad spinner with a moment of inertia $I$ is spinning with an initial angular velocity ${\omega }_0$. If a constant frictional torque ${\tau }_f$ acts to slow it down, what is the magnitude of the angular acceleration $\alpha$ of the spinner?

A disk-shaped turntable of mass $M$ and radius $R$ is initially at rest. A small mass $m$ is dropped onto the edge of the turntable and sticks to it. If the mass lands tangentially with speed $v$, what is the angular velocity $\omega$ of the turntable and mass immediately after the collision?

A thin string is wrapped around a cylindrical hoop of radius R and mass M (Fig. 11–46). One end of the string is fixed, and the hoop is allowed to fall vertically, starting from rest, as the string unwinds. Determine the angular momentum of the hoop about its cm as a function of time.

A 2.00-kg rock has a horizontal velocity of magnitude 12.0 m/s when it is at point P in Fig. E10.35. If the only force acting on the rock is its weight, what is the rate of change (magnitude and direction) of its angular momentum at this instant?