A 1 foot by 1 foot square open tank holds water to a depth o

A 1 foot by 1 foot square open tank holds water to a depth of 1 ft. It is placed on a platform weighing scale. A 6-in. X 6-in. wooden timber is lowered into the tank to a depth of 6 in. The upper end of this 6 in. X 6 in. timber is rigidly attached to the ceiling above the tank and scale. Determine the reading of the platform scale. Neglect the weight of the tank.

Solution

Since the wooden timber is hanging from the ceiling, its weight is borne by the ceiling and does not register on the scale. Only the water\'s weight registers on the scale.

Volume of water= 1ft x 1ft x 1ft = 1 cubic ft

Density of water= 62.4 lb/ft^3

Mass of 1 cubic ft of water= 62.4 lb