Density block set with wood and rock

 
Various types of wood

 
Pumice Rock

 
Petrified Wood

 
Density balls in a tank of water

 

Code Number: 2B40.61

Demo Title: Density Blocks

Condition: Excellent

Principle: Comparison of Densities

Area of Study: Fluids

Equipment: 

Density block set and mangle wood, Pumice rock, petrified wood.

Procedure:

All of these blocks have the same volume.  We have blocks of lead, brass, aluminum, maple, and balsa.  Floating these in a tank of water will give you a visual comparison of the densities.

The mangle wood, the iron wood and the lignum vitae are some of the few woods that are dense enough to sink in water.

The pumice rocks have a density which allows them to float in water much like an iceberg. 

The two silver balls both have the same mass, but the densities are vastly different.  One has a diameter of 2.86 cm and will sink in water, and the other has a diameter of 12.7 cm and will float very nicely.

References:

  • Sanjoy Kumar Pal, Soumen Sarkar, Pradipta Panchadhyayee, "Use of a Smartphone as a Density-Measuring Device", TPT, Vol. 62, #9, Dec. 2024, p. 786.
  • Joseph Priest and David F. Griffing.  "Model for an Undergraduate Physics Problem",  TPT, Vol. 28, # 4, p. 210, April 1990.
  • R. Delbourgo,  "The Floating Plank",  AJP, Vol. 55, # 9, September 1987.
  • B.Camerin Reed, "Archimedes' Law Sets A Good Energy-Minimization Example", Physics Education, Vol. 39, # 4, July 2004, p. 322.
  • Julius Sumner Miller, Q175 & A175, Millergrams II – Some More Enchanting Questions for Enquiring Minds, p. 43 & 99.