using System; using L=Science.Physics.GeneralPhysics; namespace Serway.Chapter06 { /// /// Example10: Sphere Falling in Oil /// A small sphere of mass 2.00kg is released from rest in /// a large vessel filled with oil, where it experiences a /// resistive force proportional to its speed. The sphere /// reaches a terminal speed of 5.00 cm/s. Determine the time /// constant and the time at which the sphere reaches 90.0% of /// its terminal speed. /// \tau = 5.1\times 10^{-3} sec /// t = 11.7\times 10^{-3} sec /// public class Example10 { public Example10() { } private string result; public string Result { get{return result;} } public void Compute() { // d^2y/(dt)^2 = - g - b/m dy/dt // terminal velocity = v_t = -mg/b // dy/dt = -mg/b(1-exp(-t/tau)) // tau = b/m = v_t / g double v_t = 0.05; // double m = 2.0; double g = L.Constant.AccelerationOfGravity; double tau = v_t/g; double time = -tau*Math.Log(0.1); result += Convert.ToString(tau)+" "+ Convert.ToString(time); } } } // 0.00510204081632653 0.0117478831275206