Inelastic Collisions and Coefficient of Restitution
Collisions in which momentum is conserved but kinetic energy is not; e = (relative separation speed)/(relative approach speed), with e = 0 for perfectly inelastic collisions.
What is Inelastic Collisions and Coefficient of Restitution?
Collisions in which momentum is conserved but kinetic energy is not; e = (relative separation speed)/(relative approach speed), with e = 0 for perfectly inelastic collisions.
Key formula / rule: Momentum is always conserved in the absence of external forces.
Key points
- Compute energy loss in an inelastic collision.
- Apply the coefficient of restitution to bounce problems.
Common exam trap
Assuming momentum is lost along with the kinetic energy.
Definitions
- Term
Inelastic Collisions and Coefficient of Restitution
- Meaning
Collisions in which momentum is conserved but kinetic energy is not; e = (relative separation speed)/(relative approach speed), with e = 0 for perfectly inelastic collisions.
- Term
Inelastic Collisions and Coefficient of Restitution — explanation
- Meaning
The coefficient of restitution interpolates between the elastic and perfectly inelastic limits, and the lost kinetic energy appears as heat, sound and deformation.
Learning objectives
Compute energy loss in an inelastic collision.
Apply the coefficient of restitution to bounce problems.
Formulae
- Key point
Momentum is always conserved in the absence of external forces.
- Key point
0 ≤ e ≤ 1; e = 1 elastic, e = 0 perfectly inelastic.
- Key point
Bodies move together after a perfectly inelastic collision.
Prerequisites
PHY-U1-WEP-T2-S2-C1
Common mistakes
Assuming momentum is lost along with the kinetic energy.
Using e for the ratio of speeds of a single body rather than relative speeds.
Keywords
Inelastic
Collisions
Coefficient
Restitution
Practice preview
What is conserved in an inelastic collision?…
easy
A body of mass 'm' moving with velocity 'v' collides head-on with another stationary body of the same mass 'm'. If the collision is perfectly inelastic, what is the percentage loss of kinetic energy?…
medium
In an inelastic collision, which of the following statements is true regarding energy?…
medium