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~christina~
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Homework Statement
A light baloon filled wiht helium and with a density of 0.180kg/m^3 is tied to a light string of length L= 3.00m. The string is tied to the ground, forming an "inverted" simple pendulum. The balloon is displaced slightly from it's equillibrium position, as shown in picture.
a) show that the balloon executes simple harmonic motion when it is released, i.e., show that the restoring force is a Hooke's law force.
b) What is the period of the motion?
Ignore energy lost due to air friction and take the density of air to be 1.29kg/m^3
http://img212.imageshack.us/img212/9724/58435914sp1.th.jpg
Homework Equations
?The Attempt at a Solution
a) show that the balloon executes simple harmonic motion when it is released, i.e., show that the restoring force is a Hooke's law force.
not sure how to prove this and how it should look if I do prove it when I do.
in the beginning position a):
balloon has:
buoyant force: up
gravity: down
tension: down
position b:
balloon
buoyant force: up
gravity: down?
tension: at an angle
forces on balloon
[tex]\Sum F= B-mg -T= 0 [/tex]
[tex]\Sum F'= B-mg- Tsin \theta [/tex]
I really don't know... do I combine them??
b) period of the motion
don't know how to find this as well...
please help me on this.
Thank you
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