In physics, Newton's first law of motion states that a moving body will remain in motion unless acted upon by an outside force. Similarly, a body at rest (no motion) will remain at rest unless acted upon by an outside force. This concept, called inertia, is a quality that is dependent upon the mass of the object under examination. The greater the mass of an object, the greater the force must be to oppose its inertia. A related concept is linear momentum, whose value is also determined by mass. Linear momentum, or simply momentum, is a vector quantity (having both magnitude and direction) whose value is equal to the product of the mass and velocity of an object moving in a linear (not angular) fashion. Therefore, if either (or both) the mass or velocity of an object is increased, its momentum is increased. For example, very...