Angular Momentum Consider the experiment and date below where a large massice di
ID: 1468429 • Letter: A
Question
Angular Momentum
Consider the experiment and date below where a large massice disk is dropper onto a rotating thin disk of smaller mass. Both disks have the same radii.
1) Predict whether or not the rotational kinetic energy is conserved. This is, does the initial rotational kinetic energy of the system equal the final rotational kinetic energy of the system?
3) Calculate the initial rotational kinetic energy of the system.
4) Calculate the final rotational kinetic energy of the system
5) Calculate the percent change in energy and state whether or not kinetic energy is conserved.
6) If the kinetic energy is not conserved, where did it go?
Explanation / Answer
here
1) as there will be friction acting between the disks ,
the rotational kientic energy is not conserved.
NO ,
the initial rotational kinetic energy of the system is NOT equal the final rotational kinetic energy of the system.
2)
Usig conservation of angular momentum
initial angular momentum of system = final angular mometntum
0.5 * 0.1 * 0.05^2 * 35 = (0.5 * 0.1 * 0.05^2 + 0.5 * 1.5 * 0.05^2) * wf
solving for wf
wf = 2.19 rad/s
the final angular velocity of system is 2.19 rad/s
3)
Initial rotatioanl kinetic energy = 0.5 * 0.5 * 0.1 * 0.05^2 * 35^2
Initial rotatioanl kinetic energy = 0.0766 J
the Initial rotatioanl kinetic energy is 0.0766 J
4)
final rotatioanl kinetic energy = 0.5 (0.5 * 0.1 * 0.05^2 + 0.5 * 1.5 * 0.05^2) * 2.18^2
final rotatioanl kinetic energy = 0.00474 J
final rotatioanl kinetic energy is 0.00474 J