Centripetal force is the force that acts on an object moving in a circular path, directing it towards the center of the circle.
Centripetal force can be calculated using the formula F = mv^2/r, where F is the force, m is the mass of the object, v is the velocity, and r is the radius of the circular path.
The tension in the string can be calculated using the same formula as centripetal force. In this case, F represents the tension force, m is the mass of the boy (35kg), v is the velocity, and r is the radius of the circular path.
If the boy's mass or velocity changes, the tension in the string will also change. As the mass increases, the tension will also increase, and as the velocity increases, the tension will decrease.
Some examples of centripetal force in everyday life include a car turning a corner, a roller coaster going around a loop, a satellite orbiting around the Earth, and a child swinging on a swing.