A small block on a frictionless, horizontal surface has a mass of 0.0295 kg. It
ID: 1289815 • Letter: A
Question
A small block on a frictionless, horizontal surface has a mass of 0.0295 kg. It is attached to a massless cord passing through a hole in the surface (see figure below). The block is originally revolving at a distance of 0.200 m from the hole with an angular speed of 1.55 rad/s. The cord is then pulled from below, shortening the radius of the circle in which the block revolves to 0.100 m. Model the block as a particle.
(a) Is angular momentum of the block conserved?
Yes or No
Why or why not? Please Explain
(b) What is the new angular speed?
___________ rad/s
(c) Find the change in kinetic energy of the block.
____________ L
(d) How much work was done in pulling the cord?
___________ J
Explanation / Answer
Momentum in angular and linear worlds is always conserved so the answer to 1 would be yes.
A)
Angular momentum of block = moment of inertia (I) x angular velocity (?)
I = mR