## Essential University Physics: Volume 1 (3rd Edition)

b) From the original equation, we find: $m = \frac{4}{5}=.8 \ kg$ a) We know: $T^2 = 4\pi^2 \frac{k}{m}$ $4+5m=4\pi^2\frac{k}{m}$ $(4+5(.8))^2=4\pi^2\frac{k}{.8} \\ k = 1.3 \ N/m$