Mike+Rush

**Howitzer Shot**
The picture is of a Howitzer m777 firing a shell. The photo captured the shell just feet away from the barrel after being shot out.

__**Pressure**__
The pressure of the shell being pushed out of the barrel can be seen near the tip of the barrel due to the clouds of gas that are being pushed straight through the barrel and out of the sides of the muzzle break. The gasses are pushed out to the side to reduce the amount of recoil from the pressure of the shot. The gasses behind the shell push the gun back with a large amount of force while the shell gets projected into the air out of the barrel.

__**Acceleration**__
Once the firing pin hits the cap in the back of the shell there is an ignition/explosion of sorts in the shell casing that propels the shell out of the barrel. As the shell rushes through the barrel the gases that have been created from the ignition cause it accelerate and constantly gain speed. This continues until he shell is finally propelled out of the barrel. At this point wind resistance begins to slow the shell down and decelerate which causes it to make and arch. Once the shell begins to fall back towards the ground and accelerate again until impact.

__**Force**__
The force can be seen due to the recoil of the shot as the wheels are off the ground, the gun is being pushed back, and the recoil arm is bent at an angle. If it weren't for the restraints holding the gun in place the force of the shell being pushed against the back of the gun would propel it at a high rate of speed for a very far distance. In the picture below the force of the shot actually causes the two back legs(which look like snow shovels) of the gun to dig into the ground.

Name: M777 Description: 155mm (6.1 inch) artillery cannon Weight: 7,500 lb (3,420 kg) Barrel length: 200 inches Crew: 7 +1 Distance: 15-25 miles (depending on projectile type)

[] (Video showing the firing of the M777)

In the video you can see the the way the M777 is fired and how it works. Due to the sandy and dusty ground a shock wave can be seen. This is caused by the cannons recoil pushing the air back towards the ground.