Energy, Heat, & Entropy

• • • • Development of the Steam Engine Concepts of Heat and Energy Laws of Thermodynamics Meteors and Energy – Types of Meteors – Consequences of Meteor Strikes

Definitions

• • • • • Energy = ability to do work (expressed in Joules) Work (also expressed in Joules) = Force (in Newtons) X Distance (Meters) Power (Watts) = Joules per second Kinetic Energy = ½ (kg x v 2 ) = ½ (kg x h x g) Potential Energy = (kg x v 2 ); (kg x c 2 )

James Watt

• • • Inventor and natural philosopher Member of the Lunar Society Made improvements to the original Newcomen Steam engine by adding a condensing chamber

UK (b. Scotland): 1736-1819

Watt-Boulton Steam Engine of 1784

• • • • • • • B steam valve C steam chamber E exhaust steam valve N cold water pump P piston Q regulator/governor T steam input flap controlled by regulator

Nicolas Leonard Sadi Carnot

• • • When a system goes through different energetic states and returns to its original state, a thermodynamic cycle has occurred.

While a cycle occurs, work can be done There must be an absolute low temperature

France: 1796-1832

Concepts of Heat

• • • • Considered an element in Aristotelian and Alchemical systems Even Lavoisier (founder of modern chemistry) considered it an element Motion of atoms (Boyle) Heat is a form of energy (Count Rumford)

Robert Boyle and Boyle’s Law

Image from NASA

UK (b. Ireland): 1627-1691

Benjamin Thompson, Count Rumford

• • • • Born in Massachusetts Property in Concord (formerly called Rumford), NH Royalist during the revolution (worked on force of gunpowder) Moved to London and then to Bavaria

American Colonies, UK, Bavaria, & France: 1753-1814

• • • • no mass change after heat transfer work boring cannons could boil water (it was thought that chopping up matter released caloric, but Rumford pointed out that more work equals more heat, whereas caloric would be finite in amount) cannons firing blanks get hotter than cannons firing cannonballs Published in 1798 by Royal Society

James Prescott Joule

• • Nature of heat – Heat and mechanical energy – Heat and electrical energy Formulation of the 1 st Law of Thermodynamics: Conservation of energy

England: 1818-1889

Joule’s Apparatus

Rudolph Clausius

• • Built on Carnot’s engine to develop a theory of heat that became the laws of thermodynamics

On the Mechanical

Theory of Heat (1850). A statement of the second Law of thermodynamics

Prussia (now Koszalin, Poland) 1822-1888

William Thompson, Lord Kelvin

• • • • • Clearly defined 1 st and 2 nd laws of thermodynamics Determined -273.15C is absolute zero Absolute temperature scale defined in degrees Kelvin Knighted for his role in laying transatlantic cable Used thermodynamics to determine the age of the earth

United Kingdom (b. Ireland): 1824-1907

Laws of Thermodynamics

1. Energy is conserved in a closed system, but it can be transferred from one form to another. For example heat and work are types of energy transfer.

2. Entropy – a closed system tends toward thermodynamic equilibrium 3. Entropy of a closed system approaches a constant as the temperature approaches absolute zero. That is, the entropy of a crystal at absolute zero is zero.

Forms of Energy

• • • • • Kinetic Chemical Electric Magnetic Electromagnetic radiation • Nuclear • • • • • • Ionization Elastic Sound Gravitational Intrinsic (E=mc Thermal 2 )

Entropy and Time

Carnot engine

Heat Transfer

Meteor airbursts

Chelyabinsk meteor Feb 15, 2013 Aftermath of the Tunguska event (19 years after the airburst on 30 June 1908)

Meteor Strikes

• Types of meteorites – Chondrites – Iron-nickel – Others are fragments of planets and the moon

Mechanism of the Meteor Strike

Meteor Crater Winslow Arizona Diameter 1-1.25 km

Stony asteroids that impact sedimentary rock and create a crater Impactor diameter Kinetic energy entry at atmospheric Impact energy Crater diameter 100 m (330 ft 130 m (430 ft) 150 m (490 ft) 200 m (660 ft) 250 m (820 ft) 300 m (980 ft) 400 m (1,300 ft) 700 m (2,300 ft) 1,000 m (3,300 ft) ) 47 Mt 103 Mt 159 Mt 376 Mt 734 Mt 1270 Mt 3010 Mt 16100 Mt 47000 Mt 3.8 Mt 31 Mt 71.5 Mt 261 Mt 598 Mt 1110 Mt 2800 Mt 15700 Mt 46300 Mt 1.2

km (0.75

2 km (1.2 mi) mi 2.4 km (1.5 mi) 3 km (1.9 mi) 3.8 km (2.4 mi) 4.6 km (2.9 mi) 6 km (3.7 mi) 10 km (6.2 mi) 13.6 km (8.5 mi) ) Average frequency 5200 years 11000 years 16000 years 36000 years 59000 years 73000 years 100000 years 190000 years 440000 years

Crater Copernicus Diameter 93 Km

Chicxulub Impactor

KT-Asteroid Strike 65 mya Crater diameter 180 km