I have no idea where to start with these two problems. Anyhelp would be much app

Question

I have no idea where to start with these two problems. Anyhelp would be much appreciated.
1.) A point mass of 0.022 kg is attached to a cord passing througha small hole in a frictionless, horizontal surface. The mass isinitially orbiting with speed 3.3 m/s in a circle of radius 0.4 m.The cord is then slowly pulled from below, decreasing the radius ofthe circle to r2 = 0.14 m. What is the speed of themass when the radius is r2?
2.) A mass of 0.07 kg is attachedto a cord passing through a small hole in a frictionless,horizontal surface. The mass is initially orbiting with speed 4.4m/s in a circle of radius 0.4 m. The cord is then slowly pulledfrom below, decreasing the radius of the circle tor2 = 0.13 m. Find the tension in the cord when thepoint mass is at r2. I have no idea where to start with these two problems. Anyhelp would be much appreciated.

2.) A mass of 0.07 kg is attachedto a cord passing through a small hole in a frictionless,horizontal surface. The mass is initially orbiting with speed 4.4m/s in a circle of radius 0.4 m. The cord is then slowly pulledfrom below, decreasing the radius of the circle tor2 = 0.13 m. Find the tension in the cord when thepoint mass is at r2.

Explanation / Answer

intial angular mometum of the stone                      L1 = mv1r1 final angular momentum                     L2 = mv2r2 anularmometum is conserved and hence               L1 = L2 plugging the known values we can solve for finalvelocity v2 after decreasing the length of the string .    

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