A ball on the end of a string is revolved at a uniform rate in a vertical circle of radius 72.0 cm, as shown in Fig. 5–33. If its speed is 4.00 m/s and its mass is 0.300 kg, calculate the tension in the string when the ball is (a) at the top of its path, and (b) at the bottom of its path.
Solution: The above figure is in equilibrium. Step 1 What is Static equilibrium : Static equilibrium is a form of equilibrium that occurs when an object is at rest. “Static” refers to the object being motionless while “equilibrium” refers to the object either having no net forces acting upon it or having all of its net forces balanced. So the above figure as an object is in static equilibrium, then it has no net torque and no net force.