Title: InkPhysics / Thermal physics
On every note of this deck, unless a note says otherwise:
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Front: CHECK YOURSELF
Find the root mean square speed of nitrogen molecules (molar mass 0.028 kg mol^−1) at 300 K. (R = 8.31 J K^−1 mol^−1.)
Show a hint
Write the average-KE equation with molar quantities, then solve for c_rms.
Back: Per mole: ½M(c_rms)^2 = 3RT/2, so (c_rms)^2 = 3RT/M.
(c_rms)^2 = 3 × 8.31 × 300 / 0.028 = 2.67 × 10^5 m^2 s^−2, giving c_rms = 520 m s^−1.
Faster than the speed of sound in air, which is no coincidence: sound is carried by exactly these molecules, and cannot outrun its messengers.

Front: DEFINITION
Define: Specific heat capacity.
Back: The energy needed to raise the temperature of one kilogram of a substance by one kelvin without a change of state.

Front: DEFINITION
Define: Brownian motion.
Back: The random jittering of visible particles suspended in a fluid, evidence for the random motion of the molecules bombarding them.

Front: CHECK YOURSELF
A 2.2 kW kettle holds 0.80 kg of water at 15 °C. How long does it take to reach 100 °C? (c of water = 4200 J kg^−1 K^−1; assume no losses.)
Show a hint
Price the temperature rise first, then divide by the power.
Back: Energy needed: Q = mcΔθ = 0.80 × 4200 × 85 = 2.86 × 10^5 J.
Time: t = Q/P = 2.86 × 10^5 / 2200 = 130 s, a little over two minutes.
A real kettle takes slightly longer: some energy heats the kettle body and the room, which is exactly the loss the continuous-flow method is designed to cancel.

Front: EQUATION — NOT ON THE DATA SHEET
Work done by a gas at constant pressure:
W = ?
Back: W = pΔV

Front: DEFINITION
Define: Absolute zero.
Back: The temperature at which the particles of a substance have minimum internal energy: 0 K, or −273 °C.

Front: CHECK YOURSELF
A cylinder of volume 0.020 m^3 holds gas at 250 kPa and 300 K. How many moles does it contain, and roughly how many molecules is that?
Show a hint
One equation for n, then cross the bridge.
Back: n = pV/RT = (250 × 10^3 × 0.020)/(8.31 × 300) = 2.0 mol.
Molecules: N = nN_A = 2.0 × 6.02 × 10^23 = 1.2 × 10^24.
Sense check: about four grams' worth of hydrogen or fifty-six of nitrogen, a perfectly ordinary cylinderful, and already a trillion trillion particles.

Front: DEFINITION
Define: Internal energy.
Back: The sum of the randomly distributed kinetic and potential energies of the particles in a body.

Front: DEFINITION
Define: Specific latent heat.
Back: The energy needed to change the state of one kilogram of a substance without a change of temperature.