Disk A (mA = 5 lbm) slides to the right at 45 ft/s on a smooth horizontal surfac
ID: 1856504 • Letter: D
Question
Disk A (mA = 5 lbm) slides to the right at 45 ft/s on a smooth horizontal surface. Disk B (mB = 2 lbm) is propelled from slot D by the compressed spring shown in the diagram. Disk B collides with Disk A as shown such that Disk A moves toward the pocket at point C. If the stiffness of the spring is 150 lbf/in and the coefficient of restitution is 0.5. calculate the initial compression of the spring at D.Explanation / Answer
the momentum of diskA in x direction doesnt change===>ma*45=ma*v1*6/10===>v1=75 (this is the velocity of disk a along line it is travelling after colliding disk B);Now velocity of disk A along y direction=75*8/10=60;This momentum is transffered from disk B==>mb*vb=0.5*ma*60==>vb=75;Now 0.5*k*x^2=0.5*mb*v^2===>0.5*150/(0.08333)*x^2=0.5*2*75^2==>x=2.499Ft=30 inches approx