The author of the question deserves a big FAIL. It could be another one of those copy and paste with parts left out and thus becomes ambigious, or non-sensical.

Anyways,do you know anything about hydrostatic forces, bouyancy, pressure? which is probably waht the question was supposed to get at.

What is your reasoning, or calculations, that the answer should "be equal"?

I have a scant knowledge of hydrostatics, to say the least.

My answer is just a guess, given that they are identical triangles and they are at the same depth. The only difference is their position, but the basic formulas of pressure and force do not consider the position:

Perhaps the best (most interesting, most educational) question to ask is: What is the force exerted by the bottom of the pool on the triangle? It's different for the two triangles, and when you can see why you'll have nailed this class of problems.

It's not clear which force the question is asking for. The net force on the triangle? The hydrostatic force on the triangles? Or the force exerted by the bottom the container on the triangles?

I think the hydrostatic force is being implied. Secondly, the question does not ask for a numerical answer - there is no need to know the 3rd spatial dimension features of the triangles or the pool to answer this question. No offense to anyone, but I think the question is obviously talking about prisms of equal depth into the page (so one only needs to concentrate upon the 2 dimensional view), since the answer cannot otherwise be determined with the given information (unless there were some omissions while posting the question).

My objection is that the author seems to not have considered the following simple analysis:
Since the triangles are fixed in position, there is no acceleration, and according to Fnet = ma, with acceleration a being 0, the net force Fnet = 0.
In which case, " On which triangle will a greater force be exerted?" has the answer "equal on both".

Of course,
Fnet = Fmg + Fbouyancy + Fbottom = 0
which he/she thought would be a nice tricky question.
But really, Is it?

In the absence of qualification, isn't "all" implied (all forces we can see in the diagram)? I don't think we have a grammar issue like in the last thread.

Also, in question's like this, lack of information requires the student to use the process of elimination. Is it just the hydrostatic force or also the normal force? Is triangle 2 sealed to the bottom? Turns out, with a bit of logic, those two issues cancel each other out.

Agree the question is worded too vaguely. But I think the intent of the question is hydrostatic forces. Although as correctly pointed out, the net force must be 0 since acc = 0. The magnitude of the hydrostatic forces on the individual faces is relevant. The question could have been worded, as you fill the container with more and more water, which triangle will crush first? The answer would certainly be 2. The centroid of the 2 triangle is lower than 1's, thus 2's hydrostatic pressure will be greater. One thought experiment you can do is imagine the tank is only filled to a depth just equal to the height of the triangles. Triangle 1 would have virtually no force on one entire sides. While triangle 2 would have no force only at a vertex.

this is a mechanical aptitude test, and to my mind making sense of imperfect information is a relevant part of assessing mechanical aptitude;

the question states that the "triangles" are identical, so their 3rd dimension is irrelevant - in fact you can even assume they ARE triangles with zero thickness;

one possible answer is "the net force on each triangle is zero because they are fixed in position", but that is not the best answer because it doesn't make use of all the information provided in the question; a better answer is "the force of water pressure on triangle 2 is greater because the mean depth of its surface area is greater".

So don't - it doesn't change the answer if you include the directions. In fact, solving that (if we had the numbers) provides the buoyant force (if not sealed to bottom).

If it's not sealed to the bottom, the buoyant forces are clearly equal. As is the weight of the triangles and the force required to fix them in place. No reasonable vector sum fits the "correct" answer.

If it is sealed to the bottom, one can still find a state of affairs where both triangles have zero net force. So that still fails to produce the "correct" answer.