Pressure

Regarding pressure, the following points are worth noting:

(i)                  In a static liquid at same horizontal level, pressure is same at all points.

(ii)                Pressure at  a point in a static liquid has same value in all directions

(iii)               Pressure at a point in a liquid is proportional to the depth of the point from the free surface.

(iv)              Pressure at a point in a liquid is proportional to the density of the liquid.

Pascal law for pressure of liquid 

(i)                 If gravitational attraction is negligible, in equilibrium condition, pressure is same at all points in a liquid.

(ii)               If an external pressure is applied to an enclosed fluid, it is transmitted undiminished to every direction.

Hydrolic lift, hydrolic press, Hydrolic brake work on Pascal law.

Effect of pressure on Melting Pint and Boiling Point.

(i)                  The M. P. of substances which expands on fusion increase with the increase in pressure, for example –wax.

(ii)                The m. P. of substances which contracts on fusion decreases with the increase in temperature for example –ice

(iii)               Boiling point of all the substances increases with the increase in pressure.