A uniform door of mass 22.5 kg, length 2.10 m, and width 0.900 m is kept in a vertical position by frictionless hinges on its length. A 135 g dove strikes the door at a point three-quarters of the width measured from the hinges with a horizontal speed of 20.0 m/s. The dove bounces off with a speed of 8.00 m/s in the opposite direction. State why angular momentum is a conserved quantity while linear momentum is not based on this collision.

A uniform window that is 0.700 m long and 0.500 m wide has a mass of 11.0 kg. The window is pivoted by frictionless hinges along its width and allowed to hang vertically. A 0.850 kg unlucky peregrine falcon has a level flight speed of 100 km/h when it hit the window at its center. The falcon bounces back at a speed of 60 km/h. Calculate the window's angular speed immediately after its hit by the unlucky falcon.

For a science fair project, a student uses a billiard ball of 0.16 kg and a cue stick of 0.48 kg to show rotational collisions. The ball rolls on the table and hits, with a speed of 2.0 m/s, the edge of a 1.5 m homogenous cue stick hanging at rest straight down. The cue stick rotates about a frictionless axle passing through the stick's center. Calculate the speed of the ball after the impact, assuming a perfectly elastic collision.

A uniform disk that is oriented horizontally is spinning about a vertical axis through its center at a rotational speed of 2.4 rev/s. The mass of the disk is 3.0 kg, and its diameter is 0.60 m. While the uniform disk is rotating, another smaller disk that is initially at rest and has of radius of 10 cm and a mass of 1.5 kg is placed on the center of the larger uniform disk. As a result, both of the discs begin to spin together about the same axis. Determine what the final rotational speed of this particular system will be.

Imagine a celestial object with a mass of 5.4 x 10¹⁰ kg collides with Earth at the equator, travels at a velocity of 2.4 x 10⁴ m/s, and then becomes embedded in the planet. Determine the factor by which the Earth's normal rotational frequency of one revolution per day will be affected.

A 2.0 m long wooden pole that weighs 280 g is balanced at its midpoint. A 4.0 g dart strikes the pole halfway between its midpoint and its upper edge as seen in the figure below, traveling initially at 260 m/s and departing at 120 m/s. After the collision, what is the pole's angular speed?