Adisk of mass 3.0 kg and radius 65 cm with a small mass of 0.07 kg attached at the edge is rotating at 2.2 rev/s. the small mass suddenly flies off of the disk. what is the disk's final rotation rate (in rev/s)?

Explanation:

Given that

Mass of disc,M=3 kg

radius r= 65 cm

Mass of small mass ,m=0.07 kg

Initial speed = 2.2 rev/s

If external torque is zero then angular momentum of system will remain conserve.

Moment of inertia of disc at initial condition

Moment of inertia of disc at final condition

So from conservation of angular momentum

This is final speed of disc after small mass flies off from the disc.

note: the given question is incomplete.

complete question is given below.

which is an example of kinetic energy?

a. the energy stored in ethanol  

b. a hockey puck sliding across the ice  

c. a compressed spring  

d. a ball sitting at the top of a ramp

solution: the kinetic energy is the energy posses by the virtue of the motion of the object.

in the given options, a, c and d are the example of potential energy because it is the energy posses by the virtue of the rest of the object. but option b has the kinetic energy as the object is in motion.

hence, a hockey puck sliding across the ice   is the apex example of kinetic energy.

so, the option (b) a hockey puck sliding across the ice   is the correct option.