4/21/16 4/22/16 In todays lecture there are 7 questions You will answer the 7 questions on a piece of paper. I will collect at the end of the period for points.

#1 Warm UP Think! Suppose you use a flame to add heat to 1 liter of water, and the water temperature rises by 2°C. If you add the same quantity of heat (energy) to 2 liters of water, by how much will its temperature rise?

Suppose you use a flame to add heat to 1 liter of water, and the water temperature rises by 2°C. If you add the same quantity of heat to 2 liters of water, by how much will its temperature rise? Answer: Its temperature will rise by 1°C, because there are twice as many molecules in 2 liters of water and each molecule receives only half as much energy on average.

Thermal Energy Transfer Methods of heat transfer Conduction Convection Radiation

Thermal Energy Transfer Conduction Conduction- energy transfer that occurs through collisions between particles of matter. Conduction transfers heat through material directly, through contact

Conductors conductors. Materials that conduct heat well are known as heat conductors. Example- metal is a great conductor insulators Poor conductor are called insulators #2 Why does the bathroom mat feels warmer than bathroom tile?

Conduction vs Conductors Conduction – energy transfer through contact Conductor – can transfer energy well Insulator- doe not transfer energy well

# 3 How can waking on “fire” be possible? Red hot coal is poor conductor of heat. It takes a relatively long time for heat to transfer from the glowing coal to your skin If the coal were made of red-hot metal, heat transfer through conduction would be almost instantaneous -- you would get a severe burn.burn.

Convection physical movement of material. Convection – the transfer of thermal energy due to physical movement of material. Convection transfers energy (heat) in a fluid (liquids and gasses). Thermal energy moves from a higher-temperature region to a lower-temperature region. Buoyancy often drives the fluid’s motion Movement of plate tectonics

Convection

Convection occurs in all fluids a.Convection currents transfer heat in air. a.Convection currents transfer heat in liquid. Convection

# 4 The top water will boil without melting the ice WHY? 1)water is poor conductor 2) Most of Heat travels up by convection 3) After some time conduction will heat up the glass, then ice starts melting.

Lighting a match in space What is fire? outube.com/ watch?v=tMD KeBaLWDw outube.com/ watch?v=tMD KeBaLWDw

#5 You can hold your finger beside the candle flame without harm but not above the flame. Why??

You can hold your finger beside the candle flame without harm but not above the flame. Why?? Heat travels upward by air convection. Since air is a poor conductor, very little heat travels sideways.

Radiant energy is any energy that is transmitted by radiation. From the longest wavelength to the shortest, this includes: Can travel through the vacuum of space radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays. Radiation

Radiation-the transfer of thermal energy in the form of electromagnetic waves ( light and infrared). The electromagnetic waves carry the energy. Electromagnetic radiation comes from accelerating electric charges. Example - SUN Infrared radiation

Most of the heat from a fireplace goes up the chimney by convection. The heat that warms us comes to us by radiation. Radiation

6 # How does the Sun transfer energy ? A) conduction B) convection C) radiation

7# Draw arrows showing the heat flow between individual beaker and the environment