Using a molecular view, explain why compression strength is generally less than tensile strength in polymers
What will be an ideal response?
When a compressive load is applied to a polymer, the molecules are forced closer together. If the polymer is highly crystalline, this force will simply press on the crystals with little damage, much as would happen in a crystalline solid. However, in an amorphous material, such as most plastics, there is considerable space between the polymer chains, which will allow deformation of the polymers at lower stress levels. Furthermore, the spaces allow the polymers to collapse into the holes, thus reducing the ultimate compressive strength. Hence, the compressive forces are lower for polymers than for highly crystalline materials.
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Mr. Moore has four grain bins on his farm. One bin has a diameter of 48 feet and a height of 32feet to the roof and the other three bins are 36 feet in diameter and 24 feet high to the roof.
a. What is the capacity of each bin in cubic feet? b. What is the total storage capacity of the four bins in cubic feet? c. What is the capacity in bushels of the large bin? (Note: 1 cu ft = 0.8 bu.) d. How many bushels of corn can be stored on the farm?
A ____ reacts to stop, start, or modulate the flow of water, air, or refrigerant to the system or conditioned space
A. sensor B. controller C. controlled device D. none of the above
Simplify the following ratio.
Fill in the blank(s) with the appropriate word(s).
Refrigeration systems are designed to operate year round. For this reason they are equipped with ____.
A. some type of head pressure control B. a low ambient control C. oversized evaporator coils D. both a and b