HEAT FLOW UNTIL EQULIBRIUM Standards: SC.7.P.11.4 Observe and describe that heat flows in predictable ways, moving from warmer objects to cooler ones until they reach the same temperature. Also Assesses: SC.7.P.11.1 Recognize that adding heat to or removing heat from a system may result in a temperature change and possibly a change of state. HEAT FLOW UNTIL EQULIBRIUM Essential Question: How can we reliably predict what will take place when we combine two objects with different temperatures?

BELL RINGER The diagram below shows a simplified floor plan for a small house. As the day goes on and the Sun begins to set, the rooms on the west side of the house grow warmer than the rooms on the east side, as shown by the temperatures in each room. The doors between the rooms are open. Which of the following most likely describes the direction of heat flow through the house and the effect of that heat flow on temperature? A. From Room 3 to Room 1 and Room 2 until all the rooms are about 25oC B. From Room 2 to Room 2 to Room 3 until all the rooms are about 27oC C. From Room 1 to Rooms 2 and 3 until all rooms are about 27oC D. From Room 1 to Rooms 2 and 3 until all rooms are about 25oC

Technology Resources: Brainpop: “Heat” https://www.brainpop.com/science/energy/heat/

RADIATION: The transfer of energy by electromagnetic waves. Radiation is absorbed by matter and coverted to heat energy. Does not always require matter in order to move.

CONDUCTION CONDUCTION: the transfer of heat from one object to another through direct contact (touching) of matter. Conduction occurs primarily in solids because the particles are tightly packed together. The particles themselves DO NOT move, heat energy does.

CONVECTION Convection: the transfer of thermal energy (heat) through the movement of liquids and gases. Convection occurs in FLUIDS (liquids and gases). Convection produces CURRENTS in both gases and liquids. Thermal Energy heat is carried by the particles as they move from one location to another.

Average Molecular Kinetic Energy In hotter objects, the molecules are moving very quickly and have a lot of energy. In cooler objects, the molecules are moving very slowly and have a lot of energy. When two objects with different temperatures meet, the molecules collide until they are all moving at the same speed (same temperature).

Heat Transfer: Heat will travel from an area of high temperature to an area of low temperature (but never the other way around): “How many times do you need to be told that heat moves from hot to cold?”

Equilibrium: State of Balance Equilibrium: When two objects with different temperatures mix, they will eventually reach the same temperature throughout.

“We Do” Complete this task in collaborative groups, or with teacher assistance.

Revisiting the BELL RINGER The diagram below shows a simplified floor plan for a small house. As the day goes on and the Sun begins to set, the rooms on the west side of the house grow warmer than the rooms on the east side, as shown by the temperatures in each room. The doors between the rooms are open. Which of the following most likely describes the direction of heat flow through the house and the effect of that heat flow on temperature? A. From Room 3 to Room 1 and Room 2 until all the rooms are about 25oC B. From Room 2 to Room 2 to Room 3 until all the rooms are about 27oC C. From Room 1 to Rooms 2 and 3 until all rooms are about 27oC D. From Room 1 to Rooms 2 and 3 until all rooms are about 25oC*

YOU DO TIME!

YOU DO #1 Jesse is walking on the sand at the beach one summer day. If heat is not flowing between her feet and the sand, which of the following must be true? A. The sand is wet. B. The sand is too cold for heat to flow. C. The sand is the same temperature as her feet. D. There is no friction between her feet and the sand. Correct Answer: C

YOU DO #2 On a hot summer day in Florida, Sarah was having a picnic with her family. She took a glass, which had been sitting in the Sun, and filled it with ice cubes from a cooler. Then she added lemonade from a thermos jug. Which of the following describes one direction in which heat will flow? A. From the ice cube to the glass. B. From the lemonade to the glass. C. From the lemonade to the ice cube. D. From the ice cube to the lemonade. Correct Answer: C

A. Heat from the book will move to the air. YOU DO #3 Jeffery brings a book from air-conditioned apartment to a balcony on a hot summer day. How will the cool book interact with the outside air? A. Heat from the book will move to the air. B. Heat from the air will move to the book. C. Coolness from the book will move to the air. D. Coolness from the air will move to the book. Correct Answer: B

EXIT TICKET (3 Minutes) How can we reliably predict what will take place when we combine two objects with different temperatures?