Science Project for the Difference Between Soft & Hard Wood
Softwoods like fir, pine and balsa have a simpler cell structure, weigh less and contain less energy than hardwoods like oak, maple or cherry. Depending on the age of the experimenters, there are some obvious ways to illustrate the difference between hard and soft woods. Many soft woods can be scratched with a fingernail, but hard woods cannot. A volume of pine can be weighed on a scale and it will always weigh less than an identical volume of oak. Common science projects include activities that examine the cell structure of hard and soft wood, activities that measure the buoyancy of these woods and activities that measure the energy potential of hard and soft wood.
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Cell Structure Project
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Softwoods have a cell structure with 90 to 95 percent of the cells aligned longitudinally. This structure allows these cells to conduct water up and throughout the tree. Hardwoods have a more complex structure and conduct water through pores that are absent in all softwoods. These differences, particularly the presence of pores, can be seen by examining thin slices of various hardwoods and softwoods under a microscope. The thin slices can be prepared with a block plane or chisel and students can illustrate the differences and similarities between these different types of wood with drawings.
Buoyancy Experiments
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Another project floats identically sized pieces of different hard and soft woods in water. Small weights, like fishing weights or bird shot, can be taped to each piece of wood. Each piece can be loaded until it is submerged and the results can be compared. The dry weight of each piece of wood can also be measured on a beam or electronic scale. A good starting hypothesis for young students would state that the lighter the wood, the more weight it will support in water. Students can also hypothesize that different species, pine versus cherry for example, will support some given weight and multiple samples of the same kinds of wood can be tested. Students can then report the results of their experiments.
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Measuring Heat Potential
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The most common science project with hard and soft woods measures the energy potential of at least one hardwood and at least one softwood. These experiments use measured amounts of accelerants and actually burn the woods in a controlled way, so they may not be appropriate for everybody. The area of the experiment should be covered with unglazed tiles to protect the table or counter on which the experiment is performed from fire damage. These experiments also require an accurate thermometer, a beaker, a way to measure the amount of water in the beaker and a stand or tripod of a known height.
The Heat Potential Experiment
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Students fill a beaker with 300 ml of cold water and set the beaker on a tripod or metal stand supported by a ceramic tile or other fire proof surface. The temperature of the water is measured with a thermometer and recorded. Then an identical weight of a hard or soft wood is cut into four small pieces. The pieces are doused with a measured amount of an accelerant-like lighter fluid and set on fire. The temperature of the water is measured and recorded again after the wood burns up. The experiment can be repeated multiple times with the only variable being the species of wood. The experiment can even be performed “blind,” so the person conducting the experiment does not prepare the wood or know its species. It can be accurately predicted that burning hardwood will raise the temperature of the water more than burning softwood because hardwood contains more energy.
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References
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