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Unit 8: Temperature, Heat, & Thermodynamics. Conceptual – Wednesday 4/24. Physics Fun Fact! Warm Up Problem #1 & #2 Discuss pre-lab topics Penny Lab! Friday 4/26: Finish Unit 8/Quiz. Academic – Tuesday 4/23. Happy Earth Day! – Video? Begin Unit 8 – Heat/Temperature Unit 8 Notes
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Conceptual – Wednesday 4/24 • Physics Fun Fact! • Warm Up Problem #1 & #2 • Discuss pre-lab topics • Penny Lab! • Friday 4/26: Finish Unit 8/Quiz
Academic – Tuesday 4/23 • Happy Earth Day! – Video? • Begin Unit 8 – Heat/Temperature • Unit 8 Notes • Temperature Formative (In class) • Heat Practice Problems (In Notes) • Penny Lab Next Class!
Unit 8 • 4/22 – 4/23: Notes/Practice • 4/24 – 4/25: Continue Notes & Practice/Penny Lab • 4/26 – 4/29: Conclude Unit 8/Quiz • Quiz will be the Final Unit 8 Summative since this is a short unit.
Temperature • Fahrenheit – Mostly used in the United States • 320F– Freezing Point, 2120F– Boiling Point • Celsius – Used by most of the World • 00C – Freezing Point, 1000C– Boiling Point • Kelvin – Used by the Scientific community (measured in “Kelvin” not “degrees Kelvin”) • 0K – Absolute Zero • 2.73K – Outer Space https://www.scienceabc.com/nature/universe/what-is-the-temperature-of-space.html
Absolute Zero • The theoretical coldest temperature possible. • Absolute Zero has never been reached by humans • 1997 – Nobel Prize winners accomplished T = 0.0001K • 2003 – NASA accomplished one-half billionth of 1K • 2013 – Scientists theorize “Negative Temperature” • 2017 – Scientists Accomplished 50-trillionth of 1K (0.00000000005K) http://scienceline.ucsb.edu/getkey.php?key=225 (1997) https://www.nasa.gov/vision/earth/technologies/biggest_chill.html (2003) https://www.livescience.com/25959-atoms-colder-than-absolute-zero.html (Negative Temp) https://www.sciencealert.com/we-now-have-a-new-record-on-chilling-molecules-close-to-absolute-zero (2017)
Converting Temperature Kelvin When converting to Kelvin, first find temperature in degrees Celsius. K = oC + 273 Complete the opposite to convert temperature from Kelvin oC = K - 273
Heat • A Form of energy that can be transferred between objects or created at the loss of another form of energy. Example: Stored Chemical Energy allows for Heat to be created when someone rubs their hands together. Question: In order to heat up an object, what factors contribute to how much Energy will be needed?
Heat Cont. Answer: • How much mass does the object have? (greater mass requires more energy) • How much do we need to heat it? (∆T – Change in Temperature) • How easy is it to heat? (Object like metal heat more easily than water) ^^ Something we call Specific Heat Capacity Heat is represented by Variable: QSI Unit: [ J ] – Joule Unit of Calories can also be used. This related to food Calories. https://www.physicsclassroom.com/class/thermalP/Lesson-1/What-is-Heat http://misterguch.brinkster.net/chapter16.pdf
Specific Heat Capacity • The amount of heat required to increase the temperature of an object by One degree (Often Celsius or Kelvin) Variable: cSI Unit: J/(kg ∙ oC)
Calories as Energy • In Physics, One calorie (cal) = 4.186 Joules • In Nutrition, One Calorie (Cal or kcal) = 4,186 Joules 1 Cal = 1,000 cal • A kilocalorie (kcal) is the amount of heat required to raise the temperature of 1 kilogram of water one degree Celsius. • To run a marathon, a 55kg runner needs 8,740 kJ of energy to make it to the finish line. If a Cliff Bar has 260 Calories, exactly how many will the runner need to eat to complete the marathon?
https://www.youtube.com/watch?v=REhIqRa3zO4 Thermal Expansion • The tendency for an object to change is area, volume, or shape as its temperature changes. https://www.popularmechanics.com/technology/infrastructure/a26090529/rail-company-tracks-fire-chicago/ https://www.dnainfo.com/chicago/20170109/downtown/this-is-why-metra-sets-its-tracks-on-fire-really-cold-weather
Thermal Equilibrium • The condition in which two substances in contact exchange no heat energy Example: A hot cup of tea will cool to room temperature over time
Heat Question #1 • In a half hour, a 65kg jogger can generate 8.0 x 105 J of heat. This heat is naturally removed from the human body as it regulates temperature. If the heat were not removed, how much would the jogger’s body Temperature increase? Specific Heat Capacity of the human body = 3,500 J/(kg ∙ oC) Convert your answer to degrees Fahrenheit and formulate the impact this would have on the human body.
Heat Question #2 • Determine the final temperature when 10.0 g of aluminum at 130.0 °C mixes with 200.0 grams of water at 25.0 °C. Determining the temperature of a system: Tsys = (m1c1T1 + m2c2T2)/ m1c1 + m2c2 m – Mass of the substance/object c – Specific Heat T – Temperature
Penny Lab Objective: Observe Thermodynamic changes in a controlled system and verify your findings using equations learned previously. Pre-Lab: • Process and Materials • Lab Safety • Discuss potential error during experiment