Physics article


Bullet Pierces Apple

[Extracted from: http://www.athousandandone.com/18/]

 

Hightligted words are interesting and important points.

Problem: Bullets may be small but they carry a deadly punch.

 

Result: confirmed

 

Explanation: Newton's third law of motion, you'll understand how the key to this action is reaction. Newton's third law of motion states that if an object exerts a force on another object, the second object   will exert an equal and opposite force on the first object. By "equal and opposite," we mean that the strength of the force will be exactly the same, but that it will be exerted in the opposite direction.

Bullets may be small, but they carry a deadly punch. The reason for this is momentum, which is made up of velocity times mass. In other words, what bullets lack in size, they make up for in speed. Much to the chagrin of the shooter, this momentum can cause a bullet to pierce the target and keep going without stopping. So, some bullets are designed to mushroom, or open up, upon impact for a maximum stopping power. This way, the bullet can end its journey as quickly as it began.

 

An example, in the case of the bullet, the gunpowder exerts a powerful force on the gun. As the propellant burns, it releases gases that generate an enormous amount of pressure behind the bullet. This pressure pushes against the back of the barrel, and the gun must exert an equal and opposite force on the bullet itself. In the barrel, there's nowhere to  but out. The propellant continues to burn as the bullet travels down the barrel.

 

Source: http://dsc.discovery.com/fansites/mythbusters/articles/how-a-bullet-works.html