A dike is holding back the sea from a town below sea level and it springs a leak 3.1m below the water surface. If the area of the hole in the dike is 0.012m^2, what force is needed to save the town? (The density of the sea water is 1025kg/m^3)
2006-11-03 07:48:59 · 3 answers · asked by brilliantdance12 1 in Science & Mathematics ➔ Physics
The force required is the pressure of the water at the leak times the area of the hole. You are given the area as 0.012 m^2.
The pressure of the water is dependent on the height of water above the leak, the density of the water and the acceleration of gravity (9.8 m/sec^2).
P = density x height x gravity
= 1025 kg/m^3 x 3.1 m x 9.8 m/sec^2 =
31,140 kg m/ sec^2 m^2.
A kg m/sec^2 = 1 N, so this is 31,140 N/m^2. Multiply this by the area of the hole and you get 374 N.
2006-11-03 08:05:55 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Hydrostatic pressure. Find the pressure at 3.1 meters and multiply by hole area to get force. Be careful abolut the 1 atmosphere air pressure on top of the water.
2006-11-03 08:00:55 · answer #2 · answered by modulo_function 7 · 1⤊ 0⤋
Agree totally with briliantdance , particularly about the bit where you have to be careful not to add the atmospheric pressure in cause you've already got that at the dry side of the dike.
2006-11-03 08:08:20 · answer #3 · answered by Anonymous · 0⤊ 0⤋