"Sbharris[atsign]ix.netcom.com" <sbharris@ix.netcom.com> wrote in 
message news:1124830171.861814.321780@g44g2000cwa.googlegroups.com...
| Androcles wrote:
| > "astroboy" <mr-law@rogers.com> wrote in message
| > news:1124826302.261595.297510@g44g2000cwa.googlegroups.com...
| > | Hello:
| > |
| > | I hope some one can help me in answering this question.
| > |
| > | When there is a helium balloon in a car, assuming that it attached to
| > | the seat and not touching the ceiling of the car, why is the balloon
| > | moving forward when the car is accelerated forward (speeding up) and
| > | why is the balloon moving backward when it is accelerated backward
| > | (slowing down) ?
| >
| > Air currents.
| > Androcles.
| >
| > | On the other hand, if a rock is hanging inside a car from the ceiling
| > | but not touching the seat, the rock moves backward when the car is
| > | speeding up and the rock moves forward when the car is slowing down.
| > |
| > | Why there is such a difference? I was trying so hard to draw the free
| > | body diagram for the helium balloon case but I didn't get it.
| > |
| > | Thank you very much if you can answer my question here.
| > |
|
| This guy got two right answers, and then he got yours.

You want me to draw an air current for you?
No way, go and feel one. Take a balloon with you.

Androcles.