Answer:
To make it around the circle, the tension in the string must provide the necessary centripetal force to keep the ball moving in a circle. At the top of the circle, the tension in the string must provide all the force to keep the ball moving in a circle. At the bottom of the circle, the tension in the string must provide the centripetal force in addition to the force of gravity.
We can use the centripetal force formula to solve for the minimum velocity: F_c = m * a_c
where F_c is the centripetal force, m is the mass of the ball, and a_c is the centripetal acceleration.
At the top of the circle, the centripetal force is equal to the tension in the string: F_c = T
where T is the tension in the string.
At the bottom of the circle, the centripetal force is equal to the sum of the tension in the string and the force of gravity:
F_c = T + mg
where m is the mass of the ball, g is the acceleration due to gravity (9.8 m/s^2), and T is the tension in the string.
The centripetal acceleration is given by: a_c = v^2 / r
where v is the velocity of the ball and r is the radius of the circle.
Since the circle has a radius of 0.33 m, we can substitute this into the equation for a_c: a_c = v^2 / 0.33
Combining these equations, we get:
At the top of the circle: T = m * v^2 / 0.33
At the bottom of the circle: T + mg = m * v^2 / 0.33
We can solve for the minimum velocity by using these two equations to eliminate the tension in the string: m * v^2 / 0.33 + mg = m * v^2 / 0.33
Simplifying this equation, we get: v = sqrt(0.33 * g)
Plugging in the values, we get: v = sqrt(0.33 * 9.8) = 1.81 m/s
Therefore, the minimum velocity that the ball must have to make it around the circle is 1.81 m/s