A Lil Physics... PRESSURE

Right, actually I wasn't in the mood of blogging, but I had too cause I havn't been updating for quite some time. Well, so happen that I saw something funny today when I was on a trip to Taiping, Perak, Malaysia. It's so brainless the design. Damn sad for the designer, he or she should have studied Physics before designing that thing.

Check out the jets of water... I believe by now the physics students will understand what i meant by stupid already. Well, let me explain why it is stupid to those who doesn't understand it. As you can see, the top most jet of water shot furthest and the lowest jet shot nearest. Actually, it should be the other way round. Lowest jet should have shot furthest while the highest jet should have shot nearest. Well I do understand that this is not of the normal jets but electronic pumps. Come on la!!! At least make it look a bit smart la!!!

According to the law of physics, the formula:

pressure, P = pgh

p = density of water

g = gravitational force

h = depth of water in the tank

is used to calculate the pressure exerted on the wall of the tank.

Now you can check out this diagram.

So, this should be the correct way the jets should be shooting at. Reason? Since P is directly proportional to h, then when h is higher, P should be higher and the water should have been shot further. Check out the diagram. Comparing all the three jets, the top most jet (J1) will shoot further because the h is just H1, and the h of the lowest jet (J3) is H1+H2+H3. I know some of you might have confuse already. Why not the top most jet has the h = H1+H2+H3+H4?

Yeah, many students had a rough time to actually realise that the depth is from the top of the tank to the level where the hole was placed. That's why J1 has the h of H1 only where as the h of J3 is H1+H2+H3. So as the h increases, the P also increases.

Besides this, another pressure law also explained why this phenomenon happened. the formula we are discussing this time is:

P = F/A

F = force exerted

A = surface area where the force was acting on

F = ma

in this case, a=g

m = mass of the object (liquid)

a = g = gravitational pull

P = (ma)/A

Therefore, this time the P is direcly proportional to m, while A is constant. Since the m of the volume of water for the part H1 is just a portion while compared to the volume of the water of the part H1+H2+H3. So when the mass is little, the P oso little and vice versa. Due to the P exerted is higer down below, the water will be pushed harder out of the hole and thus making is looked like it's shot further compared to the jet on top.

So by using simple Laws of pressure, we can actually show that how stupid to have this design in the public. Just imagine what would an a Physics teacher say?? I hope this is not one of my students. Hahahaha...

Note: this is just for the fun of reading and not to create any riot or what so ever, and please do correct me if i had explained it wrongly.