c) Root mean square

e) the equation pV = ⅓Nm(c2bar), where N is the number of particles (atoms or molecules) and c2bar is the mean square speed

f) root mean square (r.m.s.) speed; mean square speed

average velocity of gas particles = 0ms^-1

• gas particles move in different directions

the average speed of gas particles → measured with root mean square speed

• square each speed

• add them up

• find the mean

• square root the mean

pV = ⅓Nm(cbar²)

• pressure (Pa) × volume (m³) = ⅓ × number of particles × mass of each particle (kg) × mean square speed (ms^-1)