Q23. Mercury is filled in a tube of radius 2 cm up to a height of 30 cm . The force exerted by mercury on the bottom of the tube is $\_\_\_\_$ N . (Given, atmospheric pressure $= 10 ^ { 5 } \mathrm { Nm } ^ { - 2 }$, density of mercury $= 1.36 \times 10 ^ { 4 } \mathrm {~kg} \mathrm {~m} ^ { - } { } ^ { 3 } , \mathrm {~g} = 10 \mathrm {~m} \mathrm {~s} ^ { - 2 } , \pi = \frac { 22 } { 7 }$ )