A student carries a mercury barometer from a sea-shore town to a hill station. At the sea-shore the barometric height is 76.0cm, while at the hill station it drops to 70.0cm.
(i) Determine the decrease in atmospheric pressure between the two places. Use ρHg=13.6×103kgm−3 and g=9.80ms−2.
(ii) Using the density of air ρair=1.20kgm−3, estimate the vertical height above sea level of the hill station. Assume that the density of air is uniform in this range and neglect temperature effects.
(iii) Identify one limitation of the assumption made in part (ii) and state how it affects the accuracy of the calculated altitude.