Do Now Describe each scenario as conduction,

convection or radiation:A. A fire warming up someone’s body who is

sitting near the fireB. A pot of water heating up on the stoveC. Putting an ice pack on a burnD. Light from a lamp shines on you and

warms you up.E. Holding a mug filled with coffee to warm

up your hands

Today’s Agenda5

min• Do Now

5 min

• Important Dates25 min

• First Law of Thermodynamics

20 min

• Second Law of Thermodynamics

5 min

• Exit Ticket

Today’s Agenda5

min• Do Now

5 min

• Important Dates25 min

• First Law of Thermodynamics

20 min

• Second Law of Thermodynamics

5 min

• Exit Ticket

Important Dates & Reminders

Homework Turn-In Last Unit Exam Next Wednesday

Study Guide Tomorrow Ice Cream Lab TOMORROW! March Monthly News Project

Due Mon. April 2nd US Space and Rocket Center Field Trip

Money and permission slips due Wed. Apr. 4 Nashville College Trip (MTSU, TSU,

Belmont) Money and permission slips due

TOMORROW!

Today’s Agenda5

min• Do Now

5 min

• Important Dates25 min

• First Law of Thermodynamics

20 min

• Second Law of Thermodynamics

5 min

• Exit Ticket

The First Law of Thermodynamics basically states that in a closed system, energy can neither be created nor destroyed, only transformed or transferred. There is an energy balance in the universe.

What does this sound a lot like???

First Law of Thermodynamics

Connection to Heat Whenever heat is added to a system, it

transforms to an equal amount of some other form of energy. That form of energy is WORK.

Internal energy vs. External energy Internal energy is the energy stored within

in object/system External energy is the energy outside of an

object/system

Some visual examples of this principle

Conservation of Energy

Another Look at QQ = DE – WQ = (EF– EI) -W

Q = heat added TO THE SYSTEMDE = D in internal energyW = Work done ON THE SYSTEM

If the system does work, W is NEGATIVE

Example 1 A total of 135 J of work is done on a

gaseous refrigerant as it undergoes compression. If the internal energy of the gas increases by 156 J during the process, what is the total amount of energy removed from the gas by heat?

Example 1 Answer A total of 135 J of work is done on a

gaseous refrigerant as it undergoes compression. If the internal energy of the gas increases by 156 J during the process, what is the total amount of energy removed from the gas by heat? Q = ΔE – W Q = 156 J – 135 J Q = 21 J

Example 2 An object has an initial internal energy of

48 J. The internal energy increases to 73 J when 38 J of work is done. What is the amount of energy in the form of heat that was lost by the system during this?

Example 2 Answer An object has an initial internal energy of

48 J. The internal energy increases to 73 J when 38 J of work is done. What is the amount of energy in the form of heat that was gained by the system during this? Q = ΔE – W

Q = (EF – EI) – W Q = (73 J – 48 J) – 38 J Q = -13 J

Example 3 The internal energy of a system is

initially 27 J. After 33 J of heat is added to the system, the internal energy is measured to be 86 J. How much work was done on the system?

Example 3 Answer The internal energy of a system is

initially 27 J. After 33 J of heat is added to the system, the internal energy is measured to be 86 J. How much work was done on the system? Q = ΔE – W

Q = (EF – EI) – W 33 J = (86 J – 27 J) – W W = 26 J

Example 4 The internal energy of a system is

initially 45 J. A total of 28 J of energy is added to the system by heat while the system does -31 J of work. What is the system’s final internal energy? Q = ΔE – W

Q = (EF – EI) – W

Example 4 Answer The internal energy of a system is

initially 45 J. A total of 28 J of energy is added to the system by heat while the system does -31 J of work. What is the system’s final internal energy? Q = ΔE – W

Q = (EF – EI) – W 28 J = (EF – 45 J) – (-31) J EF = 42 J

Complete the practice problems on the Daily Organizer under First Law of Thermodynamics

Practice Problems

Today’s Agenda5

min• Do Now

5 min

• Important Dates25 min

• First Law of Thermodynamics

20 min

• Second Law of Thermodynamics

5 min

• Exit Ticket

The entropy of the universe increases in all natural processes and reactions.

Entropy is the measure of a system’s disorder.

Second Law of Thermodynamics

Second Law of Thermodynamics The entropy, or disorder, of the universe

increases in all natural processes. After cleaning your room, it always has a

tendency to become messy again. This is a result of the second law.

To understand disorder more, think about gas in a jar that is suddenly released. What is going to happen?

As the disorder in the universe increases, the energy is transformed into less usable forms

Calculating Entropy When a body

absorbs an amount of heat Q from a reservoir at temperature T, the body gains and the surroundings lose an amount of entropy Positive S: Entropy

Increased Negative S: Entropy

Decreased

Example 1 A system has 91 J of heat transferred to

it raising its temperature 15 C. What was the increase in entropy?

Example 2 A system starts out at 56 C. It loses 17 J

of heat causing its temperature to decrease to 11 C. What was the decrease in entropy?

Example 3 When a system increases its

temperature from 14 C to 29 C, its entropy also increases by 9 J/C. How much heat energy was transferred into the system?

Example 4 When a system initially at 59 C has 65 J

of heat transferred into it, its entropy increases by 14 J/C. What was the final temperature of the system?

Complete the practice problems on the Daily Organizer under Second Law of Thermodynamics

Practice Problems

Today’s Agenda5

min• Do Now

5 min

• Important Dates25 min

• First Law of Thermodynamics

20 min

• Second Law of Thermodynamics

5 min

• Exit Ticket