Fahrenheit & Celcius. Working with. Temperature Scales

Transcription

1 BRSP - 13 Page 1 Wrking with Fahrenheit & Celcius Temperature Scales Walking quickly frm the parking lt tward the terminal, I felt s warm I had t remve my jacket. The airprt thermmeter read 28 degrees. Driving hme later that night, I gt caught in a snwstrm. The guy n the lcal radi statin said a mist air mass wuld bring mre snwfall during the night as temperatures hvered arund 30. Hw wuld yu make sense f this riddle? Cnsider this fact: If yu crss the brder intanada, yu will see rad signs shwing distances in kilmeters and newspapers listing temperatures in degrees Celsius. As it turns ut, a similar situatin exists almst everywhere elsewhere in the wrld. The United States is the nly industrialized natin that des nt depend widely n the metric system f measurement. Nt t many years ag there was a plan in the U.S. t cnvert t the metric system. In 1975, Cngress passed an act t encurage the vluntary cnversin frm the English system t the metric system in all aspects f American life and cmmerce. A secnd piece f legislatin was passed in 1988 t prmte metrificatin, again vluntarily. But the prcess f cnverting t metric remains incmplete. While many U.S. businesses and virtually all scientists have made the change t metric in rder t keep pace with glbal standards, the cultural side f U.S. life remains largely rted in the ld system f weights and measures. In time this will change as mre Americans becme familiar with metric measurement and learn t use it ut f necessity. Even in the U.S., the metric system is part f the language f science and math. In scientific publicatins that still use the English system yu will almst always see the metric equivalents given next t the English units f measure. Whether yu are a scientist, a student, a writer, r a business persn, smetimes it is necessary t cnvert between English and metric when wrking with data r preparing reprts. Such is ften the case when reprting temperatures. Bth units f temperature measurement degrees Fahrenheit ( F) in the English system and degrees Celsius ( C) in the metric system are based n the freezing and biling pints f pure water at sea level. The relatinships are shwn in the scale diagram belw Freezing Pint Biling Pint

2 BRSP - 13 Page 2 The Fahrenheit scale designates the freezing pint as 32 F and the biling pint as 212 F. Ntice that there is a difference f 180 F between these tw values. The Celsius scale is based n a mre lgical arrangement in which the freezing pint is set at 0C and the biling pint at 100 C. Because this is a difference f 100 degrees, the Celsius scale is ften referred t as the centigrade scale. Lk at the tw scales fr a mment. What is the nly temperature that has the same numerical reading n bth scales? Because 100 degrees f measure n the Celsius scale is exactly equal t 180 degrees f measure n the Fahrenheit scale, ne unit C is equal t 1.8 units F. This rati cmes int play when making the cnversin frm Celsius tahrenheit and vice versa. The applicable equatins are as fllws: Change Fahrenheit telsius: C = ( F - 32) / 1.8 Change Celsius tahrenheit: F = (1.8 x C) + 32 Example 1: Change 25 F telsius. C = (25 32) / 1.8 = -3.9 C Example 2: Change 112 C tahrenheit. F = (1.8 x 112) + 32 = F When yu have side-by-side temperature scales, as in the diagram prvided, yu can btain apprximate temperature cnversins by eye. The resulting answer is clse enugh fr many purpses. Hwever, there will be times when greater precisin is needed. At ther times, the temperature values will lie utside the range f the temperature scale diagram. In thse cases the nly recurse is t use the cnversin equatins.

3 BRSP - 13 Page 3 Practice Fill in the missing temperature values in the tables belw Freezing Pint Biling Pint 1. Give a reasnable answer f temperature in degrees Fahrenheit based n yur knwledge, then make a clse estimate f the equivalent Celsius temperature using the temperature scale diagram. Rm temperature Mrning temperature n a cld day in January Maximum temperature n a July beach day Temperature at nn n a brilliant Octber day 2. Use the diagram t estimate the missing temperature values. The average surface temperature f Earth 57 The average surface temperature f Mars The recrd lw temperature n New Hampshire s Mt. Washingtn -47 The biling pint f water in Denver The biling pint f rubbing alchl (isprpanl) 82.5 The freezing pint f dry ice (carbn dixide) Use the tw temperature cnversin equatins t change the listed temperatures t F r C, as required, t the nearest degree. The average surface temperature f Venus The average surface temperature f Titan, Saturn s largest mn The maximum daytime surface temperature f Mercury The maximum daytime surface temperature f Earth s mn The apprximate maximum temperature in Earth s upper atmsphere ,700 Change Fahrenheit telsius: C = ( F - 32) / 1.8 Change Celsius tahrenheit: F = (1.8 x C) + 32

4 BRSP - 13 Page 4 Teachers Ntes Wrking with Fahrenheit & Celcius Temperature Scales Objectives: Students will learn abut the English and metric temperature scales and will perfrm cnversins between degrees Fahrenheit and degrees Celsius. Grade Level: Middle/High NSES: A3, A4, A5, A6, B4, D4, D6, E5, F10, G4, G5 NHSCF: 1a, 2a, 2b, 2c, 4a, 4b, 5g, 6d Key Cncepts The United States lags the rest f the industrialized wrld in adpting the metric system f measurement. Hwever, the scientific cmmunity and a large number f U.S. businesses are whlly dependent n the metric system, as their wrk must cnfrm t glbally accepted standards. Despite the apparent reluctance f the American general public t embrace the metric system, full metrificatin is prbably inevitable if the U.S. is t remain ecnmically cmpetitive. Fr mre n the histrical cntext, visit Answer t riddle: The persn telling the stry is abut t fly hme frm abrad. The cuntry he is leaving uses the Celsius scale. His hme cuntry, the United States, uses the Fahrenheit scale. The Fahrenheit temperature scale is part f the English system f weights and measures. The Celsius (centigrade) scale is its metric equivalent. Bth systems are calibrated t the freezing and biling pints f water. One unit n the Celsius scale is exactly equal t 1.8 units n the Fahrenheit scale. This rati is present in the tw equatins fr cnverting temperatures frm ne measurement system t the ther. An imprtant difference between the tw scales is that nly the Celsius scale starts with the zer pint set t the freezing temperature f water. Fr mst peple brn and raised in the U.S., metric measurement is nt intuitive. Americans are cnversant with feet, punds, and degrees Fahrenheit, but nt sure f themselves when it cmes t using meters, kilgrams, and degrees Celsius. The nly way t vercme this lack f familiarity is t begin using the metric system. With respect t instructin, the Celsius scale is a gd place t start. Many students are curius abut Celsius measurement, already having encuntered Celsius temperatures in their experiences and travels, if nt previusly in schl. Like all aspects f the metric system, the Celsius scale is bth lgical and systematic. While sme students may be put ff by having t learn a different system, in time they will cme t appreciate the simplicity and beauty f metric measurement. Instructin in the metric system becmes increasingly imprtant by the day. Many publicatins in bth print and electrnic media especially thse related t the sciences, technlgy, and internatinal affairs reprt facts and figures nly in metric units f measure. The trend tward metric cntinues.

5 BRSP - 13 Page 5 Extensin Activity Suggested Targets: Teacher divides the class int small grups and presents each grup with a series f items r lcatins (targets) having widely varying temperatures. Students in each grup then estimate the temperature f each target and recrd all estimates in a data table. Teacher distributes Fahrenheit labratry thermmeters. Students measure the actual Fahrenheit temperatures and recrd the data. Students then estimate the equivalent Celsius temperatures withut use f calculatrs r ther aids and recrd their estimates in the table. Teacher distributes Celsius thermmeters. Students measure the actual Celsius temperature f each target and recrd their measurements. When all data have been recrded, students in each cld tap water ht tap water lukewarm tap water chilled antifreeze ambient indr temperature ambient utdr temperature interir f refrigeratr interir f freezer rm heating radiatr air cnditiner utlet vent grup determine the ttal average difference between their initial estimates and actual Fahrenheit temperatures. They repeat this calculatin fr the differences between estimated and actual Celsius temperatures. Winning grups are thse with the lwest average differences.

6 BRSP - 13 Page 6 ANSWER KEY Practice Fill in the missing temperature values in the tables belw. 1. Give a reasnable answer f temperature in degrees Fahrenheit based n yur knwledge, then make a clse estimate f the equivalent Celsius temperature using the temperature scale diagram. Rm temperature Mrning temperature n a cld day in January Maximum temperature n a July beach day Temperature at nn n a brilliant Octber day Sample Respnses F F Use the diagram t estimate the missing temperature values. The average surface temperature f Earth 57 The average surface temperature f Mars -81 The recrd lw temperature n New Hampshire s Mt. Washingtn -47 The biling pint f water in Denver 201 The biling pint f rubbing alchl (isprpanl) 82.5 The freezing pint f dry ice (carbn dixide) Use the tw temperature cnversin equatins t change the listed temperatures t F r C, as required, t the nearest degree. The average surface temperature f Venus The average surface temperature f Titan, Saturn s largest mn The maximum daytime surface temperature f Mercury The maximum daytime surface temperature f Earth s mn The apprximate maximum temperature in Earth s upper atmsphere , ,700