When the two colliding bodies stick together and move as a single body with a common velocity after the collision, then the collision is perfectly inelastic.

Let we consider perfectly inelastic collision between two bodies of masses m₁ and m₂. The body of mass m₂ happens to the initially at rest (u₂ = 0). After the collision, the two bodies move together with common velocity v.

Therefore, Change in Kinetic Energy (∆K) is positive.

Thus, Kinetic Energy is lost mainly in the form of light, sound and heat.

#### Inelastic Collision In Two Dimension

When two bodies travelling initially along the same Straight Line collide involving some loss of kinetic energy and move after collision along different directions in a plane.

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##### NCERT Class 11 Physics Hand Written Notes Chapter-Wise

**Chapter-1 (Physical World) PDF Free Download**

**Chapter-2 (Units and Measurement) PDF Free Download**

**Chapter-3 (Motion In A Straight Line) PDF Free Download**

**Chapter-4 (Motion In A Plane) PDF Free Download**