A rope with length of L = 60cm is tied with a small ball, which moves in a circle in the vertical plane. Given the mass of the ball M = 0.5kg, find: (1) try to determine the minimum centripetal force when it reaches the highest point; (2) the minimum speed when the ball reaches the highest point and continues to move in a circle; (3) when the speed of the ball at the highest point is 3m / s, the pull of the rope on the ball. (g = 10m / S2)

A rope with length of L = 60cm is tied with a small ball, which moves in a circle in the vertical plane. Given the mass of the ball M = 0.5kg, find: (1) try to determine the minimum centripetal force when it reaches the highest point; (2) the minimum speed when the ball reaches the highest point and continues to move in a circle; (3) when the speed of the ball at the highest point is 3m / s, the pull of the rope on the ball. (g = 10m / S2)

(1) When the pull force is zero, the centripetal force is the smallest, Mg = 5N; (2) when the gravity just provides the centripetal force, the velocity is the smallest, Mg = mv2r, v = GR = 10 × 0.6 = 6m / S; (3) when the velocity of the ball is 3m / s, the resultant force of the pull force and gravity provides the centripetal force, F + Mg = mv21r, f ﹥ MV2 1R mg = 2.5n; answer: (1) the minimum centripetal force at the highest point is 5N; (2) the minimum speed at which the ball can continue to move in a circle at the highest point is 6m / S; (3) when the ball's speed at the highest point is 3m / s, the pull of the rope on the ball is 2.5n