## Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)

(a) $v = 3.93~m/s$ (b) The tension in the string is 6.2 N
(a) We can find the speed of the block as; $v = (75~rpm)(2\pi ~r)(\frac{1~min}{60~s})$ $v = (75~rpm)(2\pi)(0.50~m)(\frac{1~min}{60~s})$ $v = 3.93~m/s$ (b) The centripetal force is the net force which keeps an object moving in a circle. In this case, the tension provides the centripetal force. $T = \frac{mv^2}{r}$ $T = \frac{(0.200~kg)(3.93~m/s)^2}{0.50~m}$ $T = 6.2~N$ The tension in the string is 6.2 N.