- #1

Tanya Sharma

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- 135

## Homework Statement

A cockroach with mass m rides on a disk of mass 6.00m and radius R .The disk rotates like a merry go round around its central axis at angular speed [itex]ω_i[/itex]=1.50rad/s.The cockroach is initially at radius r=.800R,but when it crawls out to the rim of the disk .Treat the cockroach as the particle.What then is the angular speed?

Using the conservation of angular momentum the correct answer is obtained.But I am not clear why can't we use conservation of energy in this problem since no external forces are acting on the system of disk and cockroach.