Celsius-to-Fahrenheit: F = 1.8C + 32 QUESTION: What temperature reading on the Fahrenheit scale corresponds to 20.0oC? A. 20.0oF B. 68.0oF, C. 36.0oF, D. –6.67oF Celsius-to-Fahrenheit: F = 1.8C + 32 Note: by definition, 1.8 and 32 are exact F = (1.8)(20.0) + 32 = 36.0 + 32 = 68.0 What temperature reading on the Fahrenheit scale corresponds to 20.0oC? A. 20.0oF B. 68.0oF, C. 36.0oF, D. –6.67oF PAUSE CLICK We know that 20 degrees celsius is above the freezing point of water which is zero on the celsius scale and 32 on the fahrenheit scale. Therefore, the answer should be larger than 32 degrees fahrenheit. We should be able to eliminate choices A and D right away. CROSS OUT choice A and choice D. To convert a temperature reading on the celsius scale to fahrenheit, we simply multiply it by 1.8 HIGHLIGHT 1.8C then add 32. HIGHLIGHT 32 By definition, the numbers 1.8 and 32 in this formula are both exact. Plugging in the numbers, the Fahrenheit reading equals 1.8 times 20.0 plus 32 CLICK The product of 1.8 and 20.0 is 36.0. This has 3 significant digits because 20.0 has three significant digits and 1.8 is exact. CLICK Adding 36.0 and 32 gives us 68.0. The uncertainty in 36.0 is in the tenths place, while 32 is exact. Therefore, the uncertainty in the answer is expected to be in the tenths place. THe answer should, therefore, be expressed to the nearest tenth. The correct answer is B. A temperature reading of 20.0 degrees celsius is equivalent to 68.0 degrees fahrenheit. CLICK PAUSE END RECORDING

Video ID: 1A-6-1 © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08