Active Learners Reflective Learners Use both ways equally frequently More Inclined to be Active More inclined to be Reflective Sensory Leaners Intuitive Learners Use both ways equally frequently More inclined to be Sensory More Inclined to be Intuitive Active: Prefer Discussion and Active vs Reflective Learners Thinking aloud Reflective: Prefer Thinking to themselves Sensory: Sensory Prefer vs Intuitive Facts and Learners Practical Learning Intuitive: Prefer Conceptual or Creative Learning
Visual Learners Verbal Learners Use both methods equally frequently More inclined to be Visual More inclined to be Verbal Sequential Learners Global Learners Use both ways equally frequently More inclined to be Sequential More inclined to be Global Visual: Prefer Visual Visual vs Verbal Learners representations, like videos, demos or graphs, etc Verbal: Prefer Written Instructions Sequential: Prefer vs Global Instructions Learners in a logical or linear order Global: Learn the bigger picture and connect the dots
T 1 T 1 T 2 <T 2 Energy is Transferred from Environment @ T 2 to the Ice cream @ T 1 Q 1 gained by the Ice cream is > 0 Q 2 lost by the Environment is < 0 Heat will be represented as Q In this case Q 1 =-Q 2 Q > 0 System System Q < 0
Joule s Experiment James Joule 1818-1889 Temperature of water can increase by both Heating and doing Work! Temperature is directly proportional to the Thermal Energy of a system 1) Change in Thermal Energy, (E TH Final -E TH Initial ),or ΔE TH = W + Q A: Temperature and Heat (T + Q) B: Heat and Work ( Q + W) C: Work and Temperature (W + T) First Law of Thermodynamics A system where only Thermal Energy changes, the change is equal to the energy transferred into or out of the system as Work and/or Heat
Work on system W>0 First Law of Thermodynamics Work by system W<0 Energy In System ΔE TH =W+Q Energy Out Heat to system Q>0 Heat from system Q<0 2) What happens when the Volume of the gas increases? Lead Shots W Does the E TH A: Increase B: Decrease C: Remain the same Gas expands and the atoms & molecules apply less pressure on the piston. Gas has lower Internal (Thermal) energy. Q Gas Insulation T Control Knob 3) What happens when heat is transferred out of the gas? Does the E TH A: Increase B: Decrease C: Remain the same Gas atoms & molecules lose Kinetic Energy and the Internal (Thermal) energy reduces.
P 1 P 1 P 1 a P2 P2 b P 2 V 1 V 2 (a) V 1 (b) V 2 V 1 V 2 (c) 4) In all the PV diagrams A: ΔE TH (a) > ΔE TH (b) > ΔE TH (c) B: ΔE TH (a) = ΔE TH (b) = ΔE TH (c) C: ΔE TH (a) < ΔE TH (b) < ΔE TH (c) ΔE TH depends on only the Initial and Final states. It is path-independent. Q and W are path-dependent..
Hot Reservoir Q H System Q C Cold Reservoir Hot Reservoir Q H Heat is never spontaneously transferred from a colder to a hotter object. 5) Is this possible? A: Yes B: No Q C System Cold Reservoir
Hot Reservoir Hot Reservoir Q H Q H System W Q C Cold Reservoir Q C Cold Reservoir What direction will the Piston move? Right (Outward) Heat Engine What direction will the Second Piston move? Down (Outward)
An Example of a Heat Engine Stirling Engine http://www.animatedengines.com/vstirling.shtml
Hot Reservoir Q H T H Since Cyclic Process ΔE TH = 0 W out = Q H -Q C Q C Cold Reservoir T C W Out Efficiency, e = What you get What you pay What do you get? W Out =?? What do you pay for? Q H e= W out = Q H -Q C = 1 -Q C = 1 -T C where T are in Kelvin Q H Q H Q H T H This is called a Carnot Efficiency e Max < 1 But Why? Flow of Heat energy happens only when there is a difference of T. In order to have W out there should be a flowof Heat Energy and that can only happen as long as there is Some T C!!
6) 7) Ans) e = 1-(T C / T H ) Engine A: e = 1-0.7 = 0.3 or 30% Engine B: e = 1-0.625 = 0.375 or 37.5% Engine C: e = 1-0.5 = 0.5 or 50% C A Ans) e = W/ Q H Q H = 8.2kJ/ 0.25 Q H = 32.8kJ W = Q H -Q C Q C = Q H W = 24.6 kj
Hot Reservoir Hot Reservoir Q H Q C Cold Reservoir What do you get? Q C W in What do you pay for? W In Q H Q C Cold Reservoir T H What if we do work on the system to transfer Energy from Cold to Hot reservoir? T C W = + Q HC -Q C Heat Pump Instead of Efficiency e, we have COP, Coefficient of Performance = What you get What you pay for = Q C W In = Q C Q H -Q C COP= T C T H -T C How would you reduce the energy required for your Refrigerator to run? (i) Reduce temperature in your house (ii) Reduce temperature in the refrigerator (iii) Increase temperature in the refrigerator A: (i) & (ii) B: (i) & (iii) C: (ii) & (iii)
(a) Are (a) and (b) equally possible? Yes (b) Reversible Process It can be reversed Causes no change to system or surrounding Interactions at the molecular level are reversible processes
(a) Are (a) and (b) equally possible? No (b) IRReversibleProcess 8) Do either process violate the first law of thermodynamics, i.e., is Energy conserved in both cases? A: Yes B: No Then WHY is it impossible to spontaneously get process (b) to take place?
Why is it that if the interactions at the molecular level are reversible processes, then the macroscopic everyday processes are irrerversible? If there was just one ball, the probability that itwould be in Box 1 is (1/2) If there were two balls, the probability that theywould be in Box 1 is (1/2) 2 If there were ten balls, the probability that theywould be in Box 1 is (1/2) 10 Box1 N 1 Box2 N 2 Imagine there are say 10 30 balls. What do you think the probability that they are all in Box 1? VERY VERY VERY SMALL So statistically it is very likely to get a final state where N 1 N 2 T H T C Energy either way, but collisions of many many Atoms and Molecules lead to transfer from hot Even though microscopic collisions can transfer to cold, until T H = T C Equilibrium is the mostprobable state in which to be!
Energy is conserved from First law of Thermodynamics Interactions at the molecular level are reversible processes Nearly all macroscopic phenomena are irreversible, i.e., cannot trace back their path spontaneously Equilibrium is the most probable state in a system All systems evolve towards equilibrium Let us define a new term that helps us identify this unidirectionalnature of interactions (i) (ii) (iii) 9) Which box represents a most probable Spontaneous Occurrence of the atoms? A: (i) B: (ii) C : (iii) Let us define Entropyas a term used to quantify the probability that a certain state will occur, i.e., high Entropy = high probability of occurrence. Also Entropy is a measure of disorder in a system. Which of these Boxes has the highest Entropy? (iii)
T H T C Why?? All atoms in hot box have high T.E. Low entropy or high ordered system. All atoms in cold box have low T.E. This is not a spontaneously occurring situation T Equil T Equil Why?? High entropy or high disordered system. Atoms in both boxes have reached Equilibrium with the thermal energies randomly redistributed between the two boxes This is a spontaneously occurring situation Entropy increases as two systems with initially different temperatures move toward Thermal Equilibrium! The entropy of an isolatedsystem (any system spontaneously on its own) never decreases. The entropy either increases until equilibrium OR, if the system is already in equilibrium, it stays the same Second Law of Thermodynamics
All atoms and molecules in the ball move in unison, with same speed v 1 Inelastic Collision and bounce back with v 2 < v 1 Temperatures of both the ball and the wall will increase slightly. Therefore internal energy would increase for both. So will the Entropy. An isolated system evolves such that Order turns to disorder and randomness Information is lost rather than gained In all real processes the energy available for doing work decreases When another form of energy is converted to Thermal energy, there is an increase in entropy. The process will NOT spontaneously reverse!
When another form of energy is converted to Thermal energy, there is an increase in entropy. The process will NOT spontaneously reverse! Hot Reservoir Q H W All real engines operate irreversibly, due to friction and the brevity of their cycles, and therefore have an efficiency <100% Q C Cold Reservoir Heat Engine Heat engine operating in an ideal, reversible cycle, Carnot Cycle, between two energy reservoirs is the most efficient engine possible.
How are natural processes like growth possible if what they do is reduce disorder and increase complexities? None of us are ISOLATED systems http://hyperphysics.phy-astr.gsu.edu
Have a Happy Thanksgiving Please rate the lecture { Grade 1 to 4 with 4 being the highest } a) Flow of Instruction A: 1 B: 2 C: 3 D: 4 b)demo/video and Graphical aids A: 1 B: 2 C: 3 D: 4 c)explanation on Numericals A: 1 B: 2 C: 3 D: 4 d)conceptual Quality of Explanation A: 1 B: 2 C: 3 D: 4 e)overall Lecture A: 1 B: 2 C: 3 D: 4