Difference between revisions of "Data collection"

Revision as of 02:38, 24 April 2016

Unit Conversions

Why care about inches?

• In the Imperial system of measurement, inches are usually divided into halves, which means base 2 for anything shorter than 1 inch. 1/2", 1/4", 1/8", and 1/16" are commonly used measurements.
• If you view the listings for block neodymium magnets from a supplier such as Magnet4less.com, Magnet4sale.com, or KJmagnetics.com, you can find out that magnet lengths, widths, and heights are in inches.
• While the metric system is clearly more useful for scientific purposes, the base 2 system used for sub-inch imperial mesaurements is actually quite helpful for interlocking objects of different sizes together.

Useful

• 1 inch (in) = 2.54 centimeters (cm)
• 1 foot (ft) = 0.3084 meters (m)
• 1 cubic inch (in³) = 16.39 milliliters (mL) = 1.639 * 10^-5 cubic meters (m³)

Logical

• 1 amp-hour (Ah) = 3600 Coulombs (C)
• 1 milliamp-hour (mAh) = 3.6 Coulombs (C)
• 1 cubic meter (m³) = 10^3 cubic decimeters (dm³) = 10^6 cubic centimeters (cm³)
• 1 cubic meter (m³) = 10^3 liters (L) = 10^6 milliliters (mL)

Strange

• 1 gallon (gal) = 2^2 quarts (qt) = 2^3 pints (pt) = 2^4 cups (C) = 2^7 fluid ounces (fl oz.) = 2^8 tablespoons (Tbps)
• 2000 Calories (kCal) = 2.324 kilowatt-hours (kWh)
• 100 Calories per 2 Tablespoons (kCal/Tbsp) = 3,930 watt-hours per liter (Wh/L)

Surprising

• Energy of a neodymium magnet at 1.5 Tesla (T)
  • (1.5 Tesla)^2/(2*4pi*10^-7 Henries per meter) * (1.639 * 10^-5 cubic meters) = 14.67 Newton-meters (Nm) in a cubic inch
  • Conclusion: A cubic inch neomagnet, if depleted of its magnetic energy, could not even run a 15 watt light bulb for one second.
• Energy of a AA Battery (7.7 mL) at 1.5 Volts (V) and 2000 milliamp-hours (mAh)
  • (1.5 Volts * 7200 Coulombs) * (16.39 ml / 7.7 mL) = 22,990 Newton-meters (Nm) in a cubic inch (> 1,500x)
  • Conclusion: The magnetic field energy of a magnet, if depleted, would yield less than 0.1% as much energy as a battery of the same size.
• Energy of Peanut Butter at 100 Calories per 2 Tablespoons
  • (3,930 Wh/L) * (3600 Nm/Wh) * (0.01639 L) = 231,900 Newton-meters (Nm) in a cubic inch (> 15,000x)
  • Conclusion: Food sources of energy can be substantially more energy dense than typical battery tech.

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