A ball on a 1.4-meter long string is being whirled in mid-air in a horizontal circle at a constant speed v. The tension in the string is 100 N. The mass of the ball is 3.70 kg.
As usual, begin with a free-body diagram.
Follow this up with an appropriate choice of coordinate system.
Let's go with a coordinate system with +x towards the center of the circle and +y vertically up.
The tension needs to be broken into components:
Tx = T cos(q)
Ty = T sin(q)