Path of a Balloon Tied to a Thread

[Cromptu]

Question : A balloon tied to a thread whose other end is fixed to the bottom of a beaker is held such that the string is horizontal. The path traced by the balloon if it is released is ?
Answer : The path is along the arc of a circle

Please explain why the path will be along the arc of a circle..

Helppp!

 

[Doc Al]

What forces act on the balloon? Compare this to the following: What if you had a rock tied to a string and it was released from a horizontal position. What path would it take?

 

[Cromptu]

Well, the forces acting on the balloon are : the tension in horizontal direction, buoyant force and its weight.
And the rock would take tangential path wouldn't it?
But how will it go along the arc of a circle?

 

[Doc Al]

Well, the forces acting on the balloon are : the tension in horizontal direction, buoyant force and it's weight.

OK. Note that the direction of the string tension will change as the string changes position.

And the rock would take tangential path wouldn't it?

Tangential to what?

 

[Cromptu]

No wait, the rock was released from a HORIZONTAL position, so it would just take a linear path :/

 

[Doc Al]

No wait, the rock was released from a HORIZONTAL position, so it would just take a linear path :/

If there were no string attached, the rock would just fall straight down. What does the string do?

 

[Cromptu]

Well the string exerts a pulling force on it..

But how does this relate to the direction Sir?

 

[Doc Al]

Well the string exerts a pulling force on it..

Right.

But how does this relate to the direction Sir?

Don't you think that having a string pulling sideways would affect the direction of motion?

 

[Cromptu]

Yes! But how exactly would it affect the direction?