Final answer:
The pressure at the midpoint of a vertical water column can be found using the formula pressure = density x gravity x height. Plugging in the given values, we find that the pressure at the midpoint of a 40cm water column is 392 Pa.
Step-by-step explanation:
The pressure at a certain point in a vertical column of water is determined by the height of the water column above that point. The pressure increases linearly with depth. In this case, the height of the water column is 40cm, so we need to find the pressure at the midpoint of the water column. Since the water column is open at the top, the pressure at the midpoint is half of the pressure at the bottom of the column.
To find the pressure at the bottom of the column, we can use the formula:
pressure = density x gravity x height
where density is the density of water, gravity is the acceleration due to gravity, and height is the height of the water column. Plugging in the values:
pressure = (density of water) x (acceleration due to gravity) x (height of water column)
pressure = (1000 kg/m^3) x (9.8 m/s^2) x (0.40 m)
pressure = 392 Pa
So, the pressure at the midpoint of the water column is 392 Pa.