Helium Balloon In Accelerated Box

Purpose

To illustrate the affect of density on acceleration in a counterintuitive way.

Equipment

Helium balloon tethered to bottom of plastic box.

Suggestions

Ask your students to vote before performing the experiment.◙

Setup Time

5 min.

Images

c4-15

Description

A helium balloon is tethered to the bottom of an enclosed plastic box. Q: If the box is accelerated, what will the balloon do: (a) move in the direction of the acceleration, (b) move in the direcrtion opposite the acceleration, or (c) remain motionless? A: It will move in the direction of the acceleration.

References

Meiners, Physics Demonstration Experiments, Volume 1, Section 8-3.9, page 146. Meiners, Physics Demonstration Experiments, Volume 1, Section 8-3.10, page 147. Meiners, Physics Demonstration Experiments, Inertial Forces: Demonstration 8-3.2, pages 143-144. Meiners, Physics Demonstration Experiments, Section 8-3.6, page 145. Herman Medwin, Heat Does Not Always Rise, AJP 22, 571 (1954). Julius Sumner Miller, Two Demonstration Devices, AJP 30, 385-386 (1962). Hans G. Graetzer and P. W. Williams, Behavior of a Helium Balloon in a Car, AJP 31, 302-303 (1963). J. A. Van den Akker, Extension of Arch