Physics Demo Number: 037

Approximate Run Time: 10 min

States of Matter with Liquid N2 , a Racquetball, Tongs and a Balloon

Demo Description

A racquetball is placed in liquid nitrogen and then shattered when bounced against the tabletop.

A balloon is reduced to a very small volume in liquid nitrogen and then observed to re-expand upon its removal from the cold agent.

Scientific Principles

  • States of Matter

  • Phase Change

Equipment

  • Liquid Nitrogen

  • Styrofoam

  • Steel Container

  • Tongs

  • Racquetballs

  • Balloon

Equipment Location

  • The tongs, Styrofoam, steel cup, balloons and racquetballs are in [D-4-2].

  • Liquid N2 Dewar is in [D-4-1].

          The 55 lb steel plate from Kit (010), lower shelf of Steel Cart End of E-F Aisle  as a safety addition as described below.          

Instructions

After placing a racquetball in the nitrogen for several minutes, it may be thrown with sufficient force against the black lecture-hall table top to shatter it. (Note that impact with the eye-candy walls and/or the cork-floors of the lecture halls will not allow the ball to shatter.)

It may be best to use the small stepladder (in the cranny between return-air duct and building support column to the left of [D-x-x] columns) to gain access to a higher standing position relative to the table top, for purposes of effecting a high velocity hit of the ball on the table top.

One can place the metal can-Styrofoam container on the table edge near the ladder and use the tongs to extract the frozen ball.

Then either transfer the ball to your bare hand and quickly slam it against the table top, before you get frostbite, or bring a good fitting glove with you that will allow handling the frozen ball a little longer before you produce your forceful delivery of ball against the table top.

Trying to effect the throw with the tongs holding the ball will almost certainly not give the desired results.

One can also put an inflated balloon into the liquid N2 and after it shrinks down to almost nothing, lay it on the table top to watch its re-expansion as the liquid air inside it turns back to gas.

Note that there may be safety issues with using the table top ( the instructor falling from ladder or pieces of the frozen ball hitting the  instuctor or students ). Thus it is probably wise to use the 55-lb steel plate( from the bed of nails demo)  on the  cork floor as the target to throw the ball downwards against.

The plate  is seen (with its yellow  rope handles attached ) residing on a lecture table in the photo below.


Steel ball buster
  
Writeup created by David A. Burba
Copyright © 2013, Vanderbilt University.   All Rights Reserved.