Figure P9.71 shows a 100 g puck revolving in a 20-cm- radius circle on a frictionless table. The string passes through a hole in the center of the table and is tied to two 200 g weights. 

a. What speed does the puck need to support the two weights?

b. The lower weight is a light bag filled with sand. Suppose a pin pokes a hole in the bag and the sand slowly leaks out while the puck is revolving. What will be the puck's speed and the radius of its trajectory after all of the sand is gone?

Transcribed Image Text:

20 cm Pin-/ FIGURE P9.71 200 g 200 g 100 g