Question

A 2 kg disk traveling at 3.0 m/s strikes a 1.0 kg stick of length 4.0 m, that is lying flat on nearly frictionless ice. The disk strikes at the end point of the stick at a distance r=2.0 m from the stick's center. Assume the collision is inelastic and the disk adheres to the stick.The moment of inertia of the stick about its center of mass is 1.33kg*m^2.

a) Does the disk have initial linear momentum?

b) Does the disk have initial angular momentum? If so, where is the axis of rotation?

c) Does the disk have final linear momentum?

d) Does the disk have final angular momentum?

e) If ΔK = 0 for the system, would this collision make any sound?

Answer 1

a) The disk does have an initial linear momentum.

The disc is moving straight with a velocity v. SO, it will have an initial linear mementum ( p = mass*velocity)

b) The disc is not undergoing any rotation motion. So, it doesnot have any angular momentum initially.

c) The disc hits on the rod at one end and moves along with the rod.

So, the motion of the system will involved a curved path.

Since the rod is not attached anywhere, the motion of the system will be a combination of linear and circular motion.

So, it will have a final angular momentum.

d) Since the disc hits the rod at one end, the rod will follow a curved path involving a rotation and will have an angular momentum.

e) The collision is happening on a flat surface. So, there is no change in potential energy.

SO, the change in kinetic energy = 0 means that there is no energy lost during collision.

The collison is elastic.

The energy lost during a collision is converted into heat and sound. Since there is no energy lost, there will be no sound.

So, the answers are

a = yes

b = no

c = yes

d = yes

e = no