centripetal
No. The force keeping a ball on a string moving in a circle is centripetal force, i.e. force pulling the ball to the center of the circle.
The string
It's called Quipus.
Think of swinging a ball around and around on the end of a string. The ball will stay straight out at the end of the string. The ball stays suspended at the end of the string because the moving ball wants to go straight but it can't because the string is holding it -- keeping it from flying away. The force the string is exerting on the ball is called centripetal force.Moons rotate around their planets just as the ball swings around on the string. The planet's gravity acts as the string, holding the moon from flying off into space.
Put a peg in the ground where you want the centre of the circle. Tie a string to the peg - loose enough so tat the string is free to rotate around the peg. Measure 5 metres along the string, from the peg, and at that point tie something that will mark the ground - a stick, for example. Walk around the central peg, holding the stick to the ground and keeping the string taut.
A circle is perfectly round, and has one center. An ellipse is like a circle with TWO "centers", and each "center" is called a "focus". The plural of "focus" is "foci". Take a piece of string and tie a loop in each end. Put a pin through the loops, and hold it still in the center of the circle. Place the tip of your pencil at the center of the string, and you can draw a circle by keeping the string taut. Now take TWO pins, and put one pin at each end of the string; place the pins at some short distance apart, and hold them there. Place your pencil and draw, and the shape you draw will be an ellipse. The two pinpoints are the focuses, or foci, of the ellipse. Eccentricity is a measure of how far the ellipse varies from a circle. An ellipse with an eccentricity of zero _IS_ a circle, while an eccentricity of 1.0 is a straight line, with that string stretched out straight. In astronomy, every natural orbit is an ellipse.
The circumference is the length of the outside of the circle. For example, if you took a piece of string and made a circle with it, then laid the string straight, the length of the string would be the circumference. The circumference of a circle can be measured by doing two times the radius of the circle times the mathematical constant, pi.
Quipus
Picture a ball on a string being whirled about the head of an experimenter. If the string breaks, the centripetal force disappears. The ball leaves on a tangent path form its (previous) circular path. Yes, it's that simple. The string provided centripetal force, by virtue of its tensile strength, to the ball to keep that ball moving in a circle. When the string broke, there was no force left to accelerate the ball "in" and keep it moving in an arc.
the dots are to show where to put your fingers when moving from string to string
1/4
That could be a loop.