detonating land mines with water - need maths

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michaelc

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Jun 6, 2009
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Hello all, I'm looking some help with some maths as I've come up with an idea for detonating Landmines in situ using water. I'm trying to work out the amount of water that I would need. The mines need up to 15kg of weight / pressure on them to detonate.

In a nutshell the idea is many long thin plastic tubes with a 10 cm diameter are placed together veritcally (like cigarettes in a packet) and filled with water. I need to know how much water/weight each tube will need to create 15kg of pressure at the bottom.

I know that 1 litre of water weighs 1 kilogram, and the surface area at the bottom of each tube is 0.031m[sup:7x9okcl0]2[/sup:7x9okcl0] (10cm diameter) and for the purposes of this maths the tubes are weight-less

if someone could help me with the formula for finding out how much weight I would need, i'd be very grateful.

I'll put up a link to the idea if anybody else is interested.

Thanks in advance

Mick
 
The weight density of water is 9810 Newtons per cubic meter. \(\displaystyle N/m^{2}\) is measured in Pascals.

For instance, suppose we have a flat circular plate with radius 2 meters submerged horizontally in water at a depth of 3 meters.

The pressure at each point on the plate surface would be 9810*3=29,430 N/m^2=29,430 Pa.

The Force would be \(\displaystyle 9810(3)(4\pi)=369,828 \;\ N\)

The radius of a tube is .05 meters. If they are cylindrical, how tall are they?.
 
Thanks for getting back to me,

The height of the tubes can be made to any length, they will be determined by getting a force equivalent to 15kg of weight at the bottom - unless of course they are going to be several meters high, then my idea won't work.
 
15 kg of water would be .015 cubic meters.

By the volume of a cylinder formula: \(\displaystyle {\pi}(.05)^{2}h=.015\)

\(\displaystyle h=1.91 \;\ meters\)

The tubes would be just shy of 2 meters tall since they are so slim in diameter.

Is that what you're looking for?. 15 kg of water would be 15 liters or .015 m^3
 
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