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How much explosive material does a mine need to sever a human leg from the BodyHow a mine works Land mines are devices that explode when a person steps on the pressure plate. The plate pushes the firing pin down causing it to trigger the detonator to explode. The detonator is a secondary explosion that causes the primary charge to explode. The Belleville spring is used to hold the pressure plate in place until sufficient pressure is applied (for the below M14 landmine, it takes 19.8 psi of pressure to detonate). It is 40 mm high and 56 mm in diameter. The M14 mine uses .031 kg of tetryl explosive as its primary explosive. Tetryl detonates at a rate of 7193.28-7284.72 meters per second. Explosions convert the chemical potential energy into kinetic energy.Assuming a man weighs 200 lbs who is 1.5 m tall and the area of his foot is 10 in.2 and he only has one foot on the ground at a timePressure=Force/areaP=200/10P=20 psiThis is enough that he will detonate the mineImage from the Force a Mine GeneratesKe=(1/2)mv2Ke=.5(.031)(7193.28)2Ke=802029.796 JKinetic Energy can be converted to pressure with the following:P=2/3(N/V)(Ke)Air has a density of 1.29 grams per liter at sea levelP=(2/3)(1.29)( 802029.796)P=689737.8845 atm689737.8845 atm*14.7psi/atm=10139146.9 psiP=F/aThe surface area of a person can be calculated by:SA=h(cm)*m(kg).725The leg is about 9-10% of the body weight and is half the length of the bodySA=75*(8.1648).725A=104.85cm2 Converted to in2=16.2522130944261910139146.9 psi=F(lbs)/( 16.25221309442619)F=164783575.7 lbsF=732993860.753975NIt takes approximately 4000 N/1700 psi to break a femurThe bone is the strongest structure in the leg, therefore anything that can break the femur can break the joints, ligaments, muscle tissue, etc. in the leg. Determining the minimum amount of explosive material necessary to sever a legGiven that 1700psi of force can break a leg1700 psi *1atm/14.7 psi= 115.646 atmP=(2/3)(N/V)(ke)115.646=(2/3)(1.29)(ke)Ke=134.47JKe=.5mv2Ke=.5(7193.28)2m134.71=25871638.58mm=2E-6 kgIn Conclusion, the mine requires a minimum of .002 grams of tetryl to sever a human leg. The 31 gram charge easily generates the force to sever the leg many times over. Landmines are used en masse in warfare to either prevent an enemy from going a certain path or funnel them down one path. Landmines and other IED’s are very dangerous on the battlefield because they require less and less metal, so they are harder to detect and can remain active for years after the war ends.References ................
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