Q. An air puck of mass 0.2700 kg is tied to a string and allowed to revolve in the circle of radius 0.850 m on a horizontal, frictionless table. The other end of the string passes through a hole in the center of table and a mass of 0.480 kg is tied to it. The suspended mass remains in equilibrium even as the puck revolves. What is the tension of the string?
Q. An ancient club is found that contains 120.00 g of pure carbon and has an activity of 7 decays per second. Determine its age assuming that in living trees the ratio of 14C/12C atoms is about 1.10x10-12. Note that half life of carbon-14 is 5700 years and the Avogadro number is 6.020x10^23.