Question

1. a) The "Barometric formula" relates the exponential decrease in pressure as one rises higher above the surface of the earth. Which of the following constants is most readily needed to make such a calculation?

Avogadro's number, N_A

Planck's constant, h.

Fick's diffusion constant, D_f.

Boltzmann's constant, k_B.

b) True or false: The density of air is higher 1 km above the surface of the earth than at sea level?

c) True or false: Particles of the same size and shape but difference densities will 'sediment' (i.e. sink in fluid) at the same rate.

d)True of false: Two particles of the same density but of different size will 'sediment' (i.e. sink in fluid), at different speeds.

Answer 1

The "Barometric formula" relates the exponential decrease in pressure as one rises higher above the surface of the earth. Which of the following constants is most readily needed to make such a calculation

The equation is given as

P = P_o e-mgh / k_BT

where k_B is Boltzmann constant

so,

correct answer - Boltzmann's constant, k_B.

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The density of air is higher 1 km above the surface of the earth than at sea level

The density of air decreases with altitude.

therefore, density at 1 km will be less than at sea level

________________

Particles of the same size and shape but difference densities will 'sediment' (i.e. sink in fluid) at the same rate

False

Reason - Particles of different densities or size will sediment at different rates with the largest and most dense particles sinking the fastest followed by less dense and smaller particles.

___________________

Two particles of the same density but of different size will 'sediment' (i.e. sink in fluid), at different speeds

True

Reason - Particles of different densities or size will sediment at different rates with the largest and most dense particles sinking the fastest followed by less dense and smaller particles.