Intro to Angular Collisions: Videos & Practice Problems

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.

A uniform board 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. The board is unlatched and at rest when a kid strikes the board's center with a lump of their sticky molding plasticine of mass 450 g. The plasticine hits the board with a level speed of 12.0 m/s and is perpendicular to its surface. i) Determine the board's angular speed after collision. ii) Will the plasticine significantly contribute to the system's moment of inertia after the collision?

If planets orbit a central star too slowly, they will be attracted by gravity and fall into the star. Suppose a planet moves radially (not orbiting the sun or spinning on its axis) from its orbit and is embedded into the sun's equator. Taking the mass of the sun to be M, what is the mass of the planet in terms of M that increases the sun's average period of 27 days by 10%? You may find it useful to assume that the planet is far much smaller than the sun and that the sun is consistent at all points. 

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 slender, uniform copper rod with mass M and length L is positioned on a frictionless horizontal plane. A moist clay ball with mass m, traveling at speed v, strikes the rod at a point one-fifth its length from one end and sticks to it. Determine the velocity of the rod's center of mass and its angular velocity around the center post-collision.

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?

A star of mass of 2.00 × 10³⁰ kg and a radius of 7.00 × 10⁸ m spins about its own axis once every 31.0 days. An asteroid of mass of 9.55 × 10²¹ kg orbits the star at a distance of 3.20 × 10¹¹ m with an orbital period of 687 days. Ignoring the asteroid's rotation about its own axis, calculate the fraction of the total angular momentum of the star-asteroid system possessed by the asteroid.

A 1 kg disk rotating at 5 rad/s collides with a stationary 2 kg disk on a frictionless surface. After the collision, both disks rotate together. What is the final angular velocity of the system?

Which of the following describes an angular collision?

What is the angular momentum of a 2 kg mass moving at 3 m/s at a distance of 2 meters from the axis of rotation?

A 3 kg wheel rotating at 8 rad/s collides with a 5 kg stationary wheel. If the wheels stick together, what is their common angular velocity?

Convert an angular velocity of 10 rad/s to RPM.

A rotating platform has an angular speed of 4 rad/s. If a 2 kg mass is added to the edge, causing the speed to reduce to 2 rad/s, what does this indicate about the system's initial and final moment of inertia?

Two identical disks collide inelastically and start rotating together at 4 rad/s. If the initial angular speed of one disk was 8 rad/s and the other was at rest, what was the initial speed of the system?

A clockwise rotating wheel collides with a counterclockwise rotating wheel of equal mass and speed. What is the resultant angular speed if they stick together?

How does doubling the mass of one of two colliding disks affect the final angular velocity, if they have the same initial angular velocity?

What distinguishes an angular collision from a linear collision?