8.8 cm KwK 36 The 88mm KwK 36 was one of the best cannons of World War II. It was first introduced when Adolf Hitler wanted to mount the Flak 88 anti-aircraft gun on a tank. This tank was called the Tiger I. One of the most feared tanks by the allies in World War II, the American Sherman tanks could not penetrate the Tiger's thick armor. If the Tiger tank would get a shot off before the American Sherman could flank, it would most likely end in a bad way for the Sherman tank. Pictured above is the last remaining German Tiger I tank in existence. As you can see coming out from the front of the turret, that is the mighty 88mm KwK 36 Cannon. This gun is capable of penetrating 131mm of armor while using the APBC PzGr 39. More than enough to penetrate the American Sherman's 100mm of effective armor on the upper front plate. Lets get to the physics of this gun and its ammo. The 88mm KwK 36 can fire three types of ammo: APBC, APCR (Armor Piercing Composite Rigid), and HEAT (High Explosive Anti Tank). APBC:                 The most common shell used in the 88mm KwK 36, also has the best explosive mass. The shell itself has a mass of 10.2 kg and 0.059 kg of explosive filler, topping the mass out at 10.259 kg. Roughly 10 kg of steel and explosive will fly through the battlefield at a blistering muzzle velocity of 773 m/s. Using the equation for kinetic energy $KE=1/2mv^2$ we can see that the kinetic energy is 3,065,025 joules. APCR:                 APCR is a round that wasn't used much because it doesn't have the explosive filler to detonate inside the enemy tank and knock out the crew. This is purely a kinetic energy round. The mass of this round is slightly less than the APBC shell with explosive filler, but also travels at a higher speed. This round can penetrate up to 171mm of armor. The mass of this round is 7.3 kg but travels at a brisk 930 m/s. Using the kinetic energy equation, we can see that the round has 3,156,885 joules of energy. HEAT:                 HEAT is a round that was rarely used in the war because it was in the experimental phase. HEAT is still used today in the Russian made RPG-7. The HEAT round used in the 88mm KwK 36 cannon as some unique characteristics. It has the slowest velocity and a low mass. It's speed clocks in at 600 m/s and has a mass of 7.65 kg. Using the equation for kinetic energy, we find that this round has 1,377,000 joules of energy which is a lot less than both APCR and APBC.