Science November 23rd, 2015

WARM UP

•Bring your notebook, pencil and agenda to your desk•Grab a warm up from the white chair•Work on Monday’s warm up only ( do not work ahead)

Announcements• Test on Energy and Heat Transfer Tomorrow Tuesday, November 24th

• School holiday for Thanksgiving…. Wednesday, Thursday, and Friday!!

Heat Pack Lab review Block 1 only• http://www.youtube.com/watch?v=lrCzAGPwcIY

Our hand warmers….• Sodium acetate (liquid form) is placed inside pouches containing a

metal disc. • When you click the metal disc inside the pouch, a few metal particles

are released. This causes the sodium acetate to react! This is chemical energy!• The sodium acetate quickly change to a solid. This is known as

supercooling.

Let’s check our understanding…• When a liquid changes to a solid does it gain energy or lose energy?• It Loses energy….the energy is lost to the environment and we feel

this as HEAT on our hands!!!

Heat Pack Lab review Block 1 only• Sodium acetate heat pads can be used over and over again, simply

boiling them will return the solid sodium acetate back to a liquid. This means it is ready to be used again.• Pretty cool….• http://www.youtube.com/watch?v=lrCzAGPwcIY

Heat Transfer “Hot to Cold” –write in notebook and color using blue and red crayons• Energy (heat) ALWAYS flows throughout materials or across

space from hot to cold

Mr. C “Hot to Cold”• Hot to Cold video• Music video

Let’s see if we understand…• A block of ice is on a hot sidewalk. The ice melts because….• heat is moving from _______________ to _________________• (type of thermal energy transfer is _____________)

• A cold ice pack is placed on an injured elbow. The energy is moving • From _________________ to the ___________________• (type of thermal energy transfer is ______________)

• Sun shines on the pavement and the pavement gets hot. This is showing energy transfer from _____________ to ________________.• (type of thermal energy transfer is_______________)

Let’s see if we understand…• A block of ice is on a hot sidewalk. The ice melts because• heat is moving from the hot sidewalk to the ice.• (type of thermal energy transfer is conduction)

• A cold ice pack is placed on an injured elbow. The energy is moving • From the injured elbow to the ice pack• (type of thermal energy transfer is conduction)

• Sun shines on the pavement and the pavement gets hot. This is showing energy transfer from electromagnetic to thermal.• (type of thermal energy transfer is radiation)

Thermal Equilibrium…Write this calculation downHot water temperature = 90⁰ C (red container)Cold water temperature = 20 ⁰ C (blue container)If we mixed these two liquids together, what would be the equilibrium temperature? How do you know?

Share with the Class?•Volunteers?

The hot water would rise up and mix with the cold water forming convection currents. The two liquids would continue to mix until they reached an equilibrium temperature of 55⁰ C (equal temp)

90 ⁰ C + 20 ⁰ C / 2 = 55 ⁰ CEquilibrium occurs when 2 objects reach the same temperature

Convection in the atmosphere !

Write in notebook: Convection causes winds to circulate between the equator and the poles

It’s Demo Time• Conduction, Birthday Candle and a Metal Rod

It’s Demo Time• If I lay one end of a metal rod onto a hot plate, do you think I would

be able to melt a wax birthday candle? (in the middle of the rod away from the hot plate?)• Why or why not?• Yes, heat from the hot plate is conducted

through the metal rod to the birthday candle causing it to melt

“Fill in the Blank” activity• You will receive a worksheet and a word bank to complete the station

If you do not finish, complete for homework tonight while studying for the QUIZ!

Bill Nye Energy Worksheet (if needed)