Question

Nagarjun sagar dam is filled water till a height of 127 metres. If the mass of water per cubic centimeter is one gram, then find the difference in pressures acting at the following two points.
(i) Point exactly at a depth half that of the dam.
(ii) Point at the bottom of the dam.

Answer 1

Height/depth of dam=127 metres.
Density (d) `=("Mass")/("Volume")=(1 "gram")/(1 cm^(3))=1 g cm^(-3)=1000 kg m^(-3)`
(a) Height of the point =`("depth")/(2)=(127)/(2)=63.5 m`
Pressure at a point`(P_(a))=hdg`
`=63.5xx10^(3)xx10`
`=635xx10^(3)` pascals
(b) Depth of the point =127 m
Pressure at a point `(P_(b))=127xx10^(3)xx10`
`=1270xx10^(3)` pascals.
Difference in pressures `=P_(b)-P_(a)=(1270-635)xx10^(3)`
`=635xx10^(3) Pa`