Arectangular tank is filled with water to a depth of 1.5 m. its longest side measures 2.5 m. what is the moment of the force about the base on this side? is it. a) 5.5 kn. m b) 9.2 kn. m c) 13.8 kn. m d) 27.6 kn. m e) 41.4 kn. m

The correct answer is option 'c': 13.8 kNm

Explanation:

We know that moment of a force equals

The hydro static force is given by

We know that the hydrostatic pressure on a rectangular surface in vertical position is given by

For the given rectangular surface we have

Thus applying the values we get force as

This pressure will act at center of pressure of the rectangular plate whose co-ordinates is given by h/3 from base

Thus applying the calculated values we get