Question

A student’s iPhone 6 (mass = 0.129 kg) is tied to a 40 cm string and rotated at a constant speed of 5.0 m/s in a circular path.


a) What is the magnitude of the iPhone’s centripetal acceleration?



b) Find the magnitude of the centripetal force on the iPhone.

Answer 1

a)

$$a=\frac{v^2}{r}=\frac{5^2}{0.4}=62.5\frac{m}{s^2}$$

b)

$$F=ma=(0.129)(62.5)=8.06\ N$$