The string of a flying kite remains curved but pulls and pushes are passed to kite as if it is straight? How?

Question

Imagine having a a thread tied to a door? You cant pull the door unless the thread is straight. But thats not with a flying kite. Also why is there is curve in thread. Gravity ? ( its too light for the huge curve) Also think even if you had a heavy chain tied to a door instead of thread. It won't have any curves when you pull door with it. Kindly explain?

Answer 1

No string in this case is ever straight.

There are two forces acting on each bit of the string. There is the tension in the string because it is being pulled - usually more or less horizontal. And there is the force of gravity - straight down.

Gravity causes the sting to curve. The shape of the curve is called a catenary. The curve is higher if the tension in the string is higher. It is more noticeable if the string is longer.

So the string attached to the door is curved, but it is short so the curvature is small and hard to see. The string to the kite is long.

Answer 2

Great Question. Hope this makes sense to you. Every point on the string is pulled by two actions. The pull of the kite + weight of string on one side and only the weight of the string on the other side. If the string is heavy then more curve. If light then less. A silk thread will curve less than a cotton string.

Closing a door could be done with a curved string if the string were long enough and the door was high enough. Think of power lines, they curve due to weight of the line instead of being straight between two poles.

Answer 3

The curve in the string is caused by the drag of the wind upon the string Also, the attitude of the flying kite is more or less dependent on the force of the wind. which means, if the kite is experiencing total lift and the angle of attack to the wind is at maximum the kite line will be straight, otherwise the kite string will be curved due to drag forced on the string.

Answer 4

Have you studied the resultant of forces in various directions in applied maths? You've got a curved kite string in tension. Each short section of taut string contributes to the upward component of force. But the outward component of the force contributed by the lower part of the string is cancelled by the inward component of the upper part of the string, so the sideways components cancel out, and all you're left with is the same as if the string was a straight line. Like if I pushed you backwards and two others pushed you sideways in opposite directions with equal forces. They'd cancel out and you'd go backwards.