Ricochets

Ricochet, or ricocheting, is the rebound of a projectile or other object after striking a surface or obstacle. The term is commonly used in ballistics, sports, and everyday phenomena such as stones skipping on water. In physics, ricochet results from an impact that is only partially inelastic, causing a portion of the object's kinetic energy to be transferred to the surface and converted into deformation, heat, or sound, while the remainder continues with altered direction and speed.

The simplest description of a rebound follows the law of reflection, where for an ideal smooth surface the angle of incidence equals the angle of reflection. In reality, surfaces deform, friction acts at the contact patch, and the projectile may spin, all of which modify the outgoing path. The coefficient of restitution, a property of the two bodies, quantifies how much velocity is retained after impact; lower e yields a more pronounced loss of speed and a less predictable path.

Common contexts include projectiles bouncing off hard surfaces such as steel or concrete, billiard balls rebounding from cushions, and stones skipping across water. The likelihood of a ricochet depends on the incident angle, velocity, surface hardness, material properties, and surface roughness. Water skipping is sensitive to the angle and speed: too shallow or too steep a angle reduces or negates the effect.

Ricochets pose safety risks in military, law enforcement, and civilian contexts because trajectories after impact are often unpredictable. Protective design, range safety guidelines, and careful handling aim to minimize unintended ricochets.