Atoms and heatAtoms and heat

“Absolute zero” refers to:A) The size of atomsB) A new form of energyC) Motion stoppingD) A fighter jetE) A type of collision

Bose-Einstein condensation

Temperature = 170 x 10-9 K = 170 nK

The average speed of the molecules in your desk is approximately:

A) 2 inches/s [5 cm/s]B) 1 ft/s [0.3 m/s]C) 3 ft/s [1m/s]D) 1000 ft/s [330 m/s]D) 900 million ft/s [300 million m/s]

August 6, 2010

Energy content of various sources

Temperature scales

Think back to the electrolysis we did last week. We made H2 and O2. Which molecule has a faster speed at room temperature?

A) HydrogenB) OxygenC) They’re the same

speed

Moral of the tanker story?

A) Heat can melt containersB) Use caution when transporting

flammable materialsC) Pressure is proportional to temperatureD) Solids are much heavier than liquidsE) High internal pressure needs to be let out

Donut-shaped piece of metal. What happens to the hole if I heat this?

A) It gets biggerB) It gets smallerC) It stays the same size

What about a flat bar – if I heat it, will it expand more distance in the x or y direction?

A) x directionB) y directionC) same in both directions

y

x

Donut-shaped piece of metal. What happens to the hole if I heat this?

A) It gets biggerB) It gets smallerC) It stays the same size

Donuts again…

Water seems to behave similar…

But it has strange behavior…

Density of water

Sea level rise predictionsIPCC change factors 1990-2100 IS92a predictionThermal expansion 110-430 mm

Glaciers 10-230 mm[32](or 50-110 mm) [33]

Greenland ice –20 to 90 mmAntarctic ice –170 to 20 mmThawing of permafrost 0 to 5 mmTotal global-average sea level rise

(IPCC result, not sum of above)[32]

110 to 770 mm

From wikipedia, referencing IPCC report 2009

Tues 14 Sept

Are you freaking out about tomorrow’s exam?

A) Not reallyB) Sort ofC) Feeling confused on some stuffD) Need to spend today getting seriously

organizedE) Panic

What time of the year would you expect to get the best gas mileage out of your vehicle? A. SummerB. WinterC. About the same for both

Why?

Which of the following are a heat engine?A) A coal fired electric generatorB) A car engineC) A steam engine in an old fashioned train.D) A nuclear power plant's turbinesE) All of the above

Suppose the gas of atoms bouncing around in the picture has a temperature of 25 C (about room temperature). How does the pressure on the walls change if I heat up the gas to 100 C?

A) Goes up by a factor of 4B) Goes down by a factor of 2C) Goes up by a factor of 25%D) Goes up by a factor of 50%E) Stays the same

Additional clickers (not used)

If the temperature of the earth increases, a significant cause of the sea levels rising besides melting glaciers and ice would be:

A) Additional rainfallB) More oil spillsC) Thermal expansion of waterD) The increased evaporation of water

It’s summer, and you accidentally left your window open on a hot day. You are letting:

A) Hot air come inB) Cold air go out