Physics (AS & A Level) · May / June 2016 · Paper 41 · Question 2

e.g. time of collisions negligible compared to time between collisions no intermolecular forces (except during collisions) random motion (of molecules) large numbers of molecules (total) volume of molecules negligible compared to volume of containing vessel or average/mean separation large compared with size of molecules any two [2]

mass = 4.0 / (6.02 × 10 23) = 6.6 × 10–24 g or mass = 4.0 × 1.66 × 10–27 × 103 = 6.6 × 10–24 g [1]

3 kT = 2 1 m <c 2> 3 × 1.38 × 10–23 × 300 = 2 1 × 6.6 × 10–27 × <c 2> <c 2> = 1.88 × 106 (m2 s–2) r.m.s. speed = 1.4 × 103 m s–1 [3]