With L= 1.20 m, we have d= 0.60(1.20 m) = 0.72 m. Notice that if dis greater than this value, so the highest point is lower, then the speed of the ball is greater as it reaches that point and the ball passes the point. If dis less, the ball cannot go around. Thus the value we found for dis a lower limit. 68. We use conservation of mechanical energy: the mechanical energy must be the same at the top of the swing as it is initially. Newton's second law is used to find the speed, and hence the kinetic energy, at the top. There the tension force Tof the string and the force of gravity are both downward, toward the center of the circle. We notice that the radius of the circle is r= L– d, so the law can be written
This is the end of the preview. Sign up
access the rest of the document.
This note was uploaded on 05/17/2011 for the course PHY 2049 taught by Professor Any during the Spring '08 term at University of Florida.