Pressure Force on a partially submerged surface

[patricio ramos]

Homework Statement

A 6-m-high, 5-m-wide rectangular plate blocks the end
of a 5-m-deep freshwater channel, as shown in Fig. P3–75.
The plate is hinged about a horizontal axis along its upper edge
through a point A and is restrained from opening by a fixed ridge
at point B. Determine the force exerted on the plate by the ridge.

Relevant Equations

P = pgh
F = PA

Once I get the pressure, do I have to multiply times de area that is submerged (in this case it would be 25m^2), or do I take the whole area of the plate, including the part that is not submerged (in this case it would be 30 m^2)

Thanks

 

[BvU]

Hi,

Would it make a difference if the plate were 12 m high instead of 6 ?

There is something else going wrong in your line of thinking, it seems: what do you mean with 'the pressure' ?

Why don't you get started on your solution and post what you have worked out. PF will steer you if things go wrong