Answer:
The magnitude of swing's tension is 0.71 N.
Step-by-step explanation:
Given;
mass of the ball, m = 18 g = 0.018 kg
angular speed of the ball, ω = 1 rev/s
radius of the motion, r = 1 m
Angular speed in rad/s is calculated as follows;

Linear speed of the ball, v;
v = ωr
v = 2π x 1
v = 2π m/s
The magnitude of swing's tension is calculated as the centripetal force keeping the ball in circular motion.

Therefore, the magnitude of swing's tension is 0.71 N.