Question

Before the experiment, the total momentum of the system is 2.5 kg m/s to the right and the kinetic energy is 5J. After the experiment, the total momentum of the system is 2.5 kg m/s to the right and the kinetic energy is 4J.
a. This describes an elastic collision (and it could NOT be inelastic).
b. This describes an inelastic collision (and it could NOT be elastic).
c. This is NEITHER an elastic collision nor an inelastic collision.
d. This describes a collision that is EITHER elastic or inelastic, but more information is required to determine which.

Answer 1

Answer:

Option (b) is correct.

Explanation:

Elastic collision is defined as a collision where the kinetic energy of the system remains same. Both linear momentum and kinetic energy are conserved in case of an elastic collision.

Inelastic collision is defined as a collision where kinetic energy of the system is not conserved whereas the linear momentum is conserved. This loss of kinetic energy may due to the conversion to thermal energy or sound energy or may be due to the deformation of the materials colliding with each other.

As given in the problem, before the collision, total momentum of the system is $2.5~Kg~m~s^{-1}$ and the kinetic energy is $5~J$. After the collision, the total momentum of the system is  $2.5~Kg~m~s^{-1}$, but the kinetic energy is reduced to $4~J$. So some amount of kinetic energy is lost during the collision.

Therefor the situation describes an inelastic collision (and it could NOT be elastic).