A 1 m long thin rod stands on the ice surface. The lower end of the rod is mounted on a rotating axis. The rod is hit by a pointed projectile at the height of 0.75 m from the lower end at a speed of 
and bounces off it elastically at a speed of 
. The mass of the rod is 3 kg and that of the projectile is 20 g.
Rod on the ice surface
At what angular velocity does the rod begin to rotate about its axis?
What is its angular velocity if the axis of rotation is in the middle of the length of the rod?
The moment of inertia of a rod rotating around its end is 
. If it rotates around an axis in the middle, then the moment of inertia is 
.
when the axis is at the lower end of the rod.
when the axis is in the middle of the rod length.
