Question

two objects move toward each other, collide, and separate. if there was no net external force acting on the objects, but some kinetic energy was lost, then
a. the collision was elastic and total linear momentum was not conserved
b. the collision was not elastic and total linear momentum was conserved
c. the collision was elastic and total linear momentum was conserved
d. the collision was not elastic and total linear momentum was not conserved

Explanation:

• Momentum conservation: According to the law of conservation of linear momentum, if there is no net external force acting on a system (in this case, the two - object system), the total linear momentum of the system is conserved. So, options a and d which claim that momentum is not conserved are incorrect.
• Elastic vs inelastic collision: In an elastic collision, kinetic energy is conserved. Since it is given that some kinetic energy is lost, the collision is not elastic.

Answer:

B. the collision was not elastic and total linear momentum was conserved