Current location - Plastic Surgery and Aesthetics Network - Wedding supplies - (20 10? Two strings with different lengths are hung at the same point, and a ball with the same mass is tied at the other end, so that they are on the same horizontal plane.
(20 10? Two strings with different lengths are hung at the same point, and a ball with the same mass is tied at the other end, so that they are on the same horizontal plane.
As shown in the figure, the force analysis of one of the balls is influenced by gravity and rope tension. Because the ball moves in a uniform circle, it works together to provide centripetal force;

Combining gravity and tension, the resultant force points to the center of the circle, which is obtained from the geometric relationship. The resultant force is f = mg tan θ ①;

According to the centripetal force formula, f = mω 2r ②;

Let the height difference between the rope and the suspension point be h, and we can get from the geometric relationship: r = htanθ ③;

From ① ② ③, ω=gh, which has nothing to do with the length and rotation radius of the rope;

And by T = 2ωω, so the period has nothing to do with the length of the rope and the radius of rotation, so a is correct;

From v=wr, it can be seen that the rotation radii of the two balls are different, so the linear velocity is different, so B is wrong;

Rope tension: T=mgcosθ, so the rope tension is different, so C is wrong;

From F=ma=mω2r, it can be seen that the rotation radii of the two balls are different, so the centripetal force is different, so D is wrong;

So choose a.