Problem $20$:

A puck of mass $m=54\mathrm{.}0g$ is attached to a taut cord passing through a smail hole in a frictionless, horizontal surface, as shown in the figure below. The puck is initialify orbiting with speed $v_l=1\mathrm{.}40\frac{m}{s}$ in a circle of radius $r_i=0\mathrm{.}310m.$ The cord is then slowly pulled from below, decreasing the radius of the circle to $r=0\mathrm{.}150m.$

What is the puck's speed at the smaller radius, $r=0\mathrm{.}150m?$

$($A$)4\mathrm{.}43\frac{m}{s}$

$($B$)3\mathrm{.}76\frac{m}{s}$

$($C$)7\mathrm{.}62\frac{m}{s}$

$($D$)8\mathrm{.}56\frac{m}{s}$

$($E$)2\mathrm{.}89\frac{m}{s}$