perplexus.info :: Science : Balloon in a car

Balloon in a car (Posted on 2004-12-16)

You work for a balloon delivery service and you are delivering a single, helium-filled balloon in your car. To prevent the balloon from bouncing around on the ceiling while you are driving you have tied a string with a weight on it to the balloon. The weight is resting on the floor and the balloon is floating just below the ceiling.

When you accelerate, does the balloon stay where it is, move backward, or move forward? What does it do when you make a turn?

Assume all the windows are closed and the vents are turned off so there is no air flow inside the car to affect the balloon.

Submitted by Sing4TheDay

Rating: 3.6667 (3 votes)

Solution: (Hide)

As the car accelerates forward, inertia forces the air inside the car backward compressing the air behind the balloon and pushing it forward. This is because the air is heavier than the helium-filled balloon, and thus acts as all heavy things do in a car that's accelerating: move backwards. Similarly, when rounding a curve, the balloon moves into the curve..

(from Mathematical Carnival by Martin Gardner)

Comments: ( You must be logged in to post comments.)

Subject	Author	Date
Rental Car Service in UK	CodyDunning	2023-08-07 23:53:18
Puzzle Thoughts	K Sengupta	2023-04-17 12:26:07
A practical application	Steven Lord	2020-12-09 20:31:31
re(3): SOLUTION IS WRONG	Sing4TheDay	2008-12-23 14:35:40
re(2): SOLUTION IS WRONG	JayDeeKay	2007-05-09 18:54:24
re: SOLUTION IS WRONG	Ansh	2006-10-07 14:53:01
SOLUTION IS WRONG	Jud	2005-08-11 13:26:52
re: No Subject	Hugo	2005-07-29 18:20:17
No Subject	Jason Taylor	2005-07-29 17:46:26
Re: 'Relativity' solution	François	2005-01-06 18:04:00
worthless	vije	2004-12-29 14:58:29
scuba	Larry	2004-12-17 14:34:19
re: hmm....	Sam	2004-12-17 08:56:11
hmm....	John	2004-12-17 05:48:28
re(2): Solution (spoilers)	Sing4TheDay	2004-12-16 17:03:16
re: Same solution, different reasoning	Michael Cottle	2004-12-16 16:47:18
Same solution, different reasoning	Sam	2004-12-16 15:52:59
re(3): Solution (spoilers)	nikki	2004-12-16 15:48:32
re(2): Solution (spoilers)	Eric	2004-12-16 15:20:51
re: Solution (spoilers)	nikki	2004-12-16 14:38:10
Solution	Eric	2004-12-16 13:40:40

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