using System; using L=Science.Physics.GeneralPhysics; namespace Serway.Chapter11 { /// /// Example08: The Merry-Go-Round /// A horizontal platform in the shape of a circular disk /// rotates freely in a horizontal plane about a frictionless /// vertical axle. The platform has a mass M = 100 kg and a radius /// R = 2.0m. A student whose mass is m = 60 kg walks slowly from /// the rim of the disk toward its center. If the angular /// speed of the system is 2.0 rad/sec when the student is at /// the rim, what is the angular speed when he reaches a point /// r = 0.5 m from the center? /// w_f = 4.1 rad/sec /// public class Example08 { public Example08() { } private string result; public string Result { get{return result;} } public void Compute() { L.Mass M = new L.Mass(); M.kg = 100.0; L.Length R = new L.Length(); R.m = 2.0; L.RigidBody disk = new L.RigidBody(M); disk.SetCylinder(R,R); L.MomentOfInertia Ii = new L.MomentOfInertia(); Ii.ZZ = disk.RigidBodyMomentOfInertia.ZZ + 60.0*R.m*R.m; L.AngularVelocity wi = new L.AngularVelocity(); wi.Z = 2.0; L.AngularMomentum Li = new L.AngularMomentum(Ii,wi); L.MomentOfInertia If = new L.MomentOfInertia(); If.ZZ = disk.RigidBodyMomentOfInertia.ZZ + 60.0*0.5*0.5; L.AngularVelocity wf = new L.AngularVelocity(); wf.Z = Li.Z / If.ZZ; result+=wf.ToString(); } } } //0 +/- 0 i +0 +/- 0 j +4.09302325581395 +/- 0 k (rad/s)