# Do perfectly inelastic collisions conserve kinetic energy?

**collisions**,

**perfectly inelastic collisions**don't

**conserve energy**, but they

**do conserve**momentum. While the total

**energy**of a system is always conserved, the

**kinetic energy**carried by the moving objects is not always conserved.

Keeping this in view, what is the decrease in kinetic energy during the collision?

K.E. Lost in Inelastic **Collision** In the special case where two objects stick together when they **collide**, the fraction of the **kinetic energy** which is lost in the **collision** is determined by the combination of conservation of **energy** and conservation of momentum.

**If**the

**kinetic energy**is the same, then the

**collision**is elastic.

**If**the

**kinetic energy**changes, then the

**collision**is inelastic regardless of

**whether the**objects stick together or not. In either case, for

**collisions**with no external forces, momentum is

**conserved**.

Also know, what is conserved in perfectly inelastic collision?

**Elastic** and **Inelastic Collisions**. A **perfectly elastic collision** is defined as one in which there is no loss of kinetic energy in the **collision**. Momentum is **conserved** in **inelastic collisions**, but one cannot track the kinetic energy through the **collision** since some of it is converted to other forms of energy.

Another common **example** of a **perfectly inelastic collision** is known as the "ballistic pendulum," where you suspend an object such as a wooden block from a rope to be a target.