The centripetal problem
An air puck of mass 0.028 kg is tied to a string and allowed to revolve in a circle of radius 1.1 m on a frictionless horizontal surface. The other end of the string passes through a hole in the center of the surface, and a mass of 1.9 kg is tied to it, as shown in the figure. The suspended mass remains in equilibrium while the puck revolves on the surface. The acceleration of gravity is 9.81 m/s2 .a) What is the magnitude of the force that maintains circular motion acting on the puck? Answer in units of N.
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1 solution
The weight of the suspended mass (M) provides the central force that maintains the circular motion of the puck. Centripetal force = mv²/r where m = mass of puck and r the radius of motion, v is the tangential speed. Mg=mv^2/r =1.9*9.81=18.64N.