In: Physics
A merry-go-round modeled as a disk of mass M = 9.00 101 kg and radius R = 2.20 m is rotating in a horizontal plane about a frictionless vertical axle (see figure).
(a) After a student with mass m = 88.0 kg jumps onto
the merry-go-round, the system's angular speed decreases to 2.10
rad/s. If the student walks slowly from the edge toward the center,
find the angular speed of the system when she reaches a point 0.490
m from the center.
rad/s
(b) Find the change in the system's rotational kinetic energy
caused by her movement to the center.
J
(c) Find the work done on the student as she walks to r =
0.490 m.
J
Use the values from the PRACTICE IT section to answer this exercise.
(a) Find the angular speed of the merry-go-round before the
student jumped on, assuming the student didn't transfer any
momentum or energy as she jumped on the merry-go-round.
rad/s
(b) By how much did the kinetic energy of the system change when
the student jumped on? Notice that energy is lost in this process,
as should be expected, since it is essentially a perfectly
inelastic collision.
KEf − KEi
= J