The figure shows a 100 puck revolving in a 20 radius circle on a frictionless ta
ID: 1909653 • Letter: T
Question
The figure shows a 100 puck revolving in a 20 radius circle on a frictionless table. The string passes through a hole in the center of the table and is tied to two 200 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 after all of the sand is gone? c)What will be the radius of its trajectory after all of the sand is gone?
Explanation / Answer
a)let T is the tension in the string m1=200=0.2kg , m2=200=0.2kg ,m=100g=0.1kg , r=20cm=0.2m T=m1g+m2g =0.4*10=4N also T is equal to the centripetal force(F) F=T mv^2/r = 4 0.1*v^2/0.2=4 v^2=8 v=2*sqrt(2)=2.82m/s b)after the removal of lower mass T=2N F=mV^2/r mV^2/r=2 V^2=4 V=2m/s