How Is the Weight of a Bird Calculated When It Sits on a Kite?

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SUMMARY

The weight of a bird sitting on a kite can be calculated by analyzing the forces acting on the kite at two different angles of the string. Initially, the kite is at a 50-degree angle with a tension of 15 Newtons, resulting in a horizontal force of 9.64 N and a vertical force of 11.49 N. When the bird lands, the angle changes to 30 degrees, and the new horizontal force remains 9.64 N, while the vertical force decreases, leading to a calculated weight of the bird at approximately 5.924 Newtons. The tension in the string does not remain constant and must be recalculated based on the new equilibrium conditions.

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  • #31
I say decelerated, because, initially, the kite has a tension and in equilibrium, but when the weight exerts a force on the kite, the kite moves with some force that will accelerate the kite to move down y axis, yet somehow the kite stops. I suspect that there then would exist a deceleration sometime between the weight exerted by the bird on the kite and when the new equilibrium position is reached. I think there is a change in acceleration with respect to time in this sense, because the wind force is such a weird thing to deal with where its force increases with increasing velocity. So, I mean, what do you think about the idea of the wind force in this situation?

Also, I want to note that the components of the tension do in fact change with a change in angle. As the angle gets shorter, the tension in the y direction decreases and that's also partially why this is a strange situation to me.
 
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  • #32
Rayquesto said:
I say decelerated, because, initially, the kite has a tension and in equilibrium, but when the weight exerts a force on the kite, the kite moves with some force that will accelerate the kite to move down y axis, yet somehow the kite stops. I suspect that there then would exist a deceleration sometime between the weight exerted by the bird on the kite and when the new equilibrium position is reached. I think there is a change in acceleration with respect to time in this sense, because the wind force is such a weird thing to deal with where its force increases with increasing velocity. So, I mean, what do you think about the idea of the wind force in this situation?

Also, I want to note that the components of the tension do in fact change with a change in angle. As the angle gets shorter, the tension in the y direction decreases and that's also partially why this is a strange situation to me.

What you say about a real kite in a real wind with a real string and a real bird is all correct. However an important part of the original post/question was:
"Assume that the force exerted by the wind on the kite alone is exactly the same as the force exerted by the wind on the kite and bird together"

This immediately made the problem a simplified, idealised situation, so real world logic is no longer that important.

As you obviously realize, the behaviour of wind, with the kite tipping at different angles is extremely complex - that is why, in this case, a greatly simplified situation is to be assumed.

Many problems we are presented with in school/college physics are simplified/idealised presentations of an every day occurrence, and we have to be ready to go with that.

When was the last time you had to deal with a satellite in elliptical orbit, and allow for added air resistance at the points where it is nearer the Earth?
We mostly idealise to perfectly circular orbit around a perfectly spherical Earth of uniform density.
We mostly assume air resistance is insignificant [ignored], or constant regardless of speed.
Surfaces are magically frictionless etc. etc.
Even when launching a rocket that achieves enormous speed, we still ignore the air resistance.

This stopped
 

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