# Homework Help: Laws of Fluids

1. Aug 21, 2011

### 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!

2. Aug 21, 2011

### Staff: Mentor

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?

3. Aug 21, 2011

### 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?

Last edited: Aug 21, 2011
4. Aug 21, 2011

### Staff: Mentor

OK. Note that the direction of the string tension will change as the string changes position.
Tangential to what?

5. Aug 21, 2011

### Cromptu

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

6. Aug 21, 2011

### Staff: Mentor

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

7. Aug 21, 2011

### Cromptu

Well the string exerts a pulling force on it..

But how does this relate to the direction Sir?

8. Aug 21, 2011

### Staff: Mentor

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

9. Aug 21, 2011

### Cromptu

Yes! But how exactly would it affect the direction?