Final answer:
In Newton's cradle, the swinging ball bearings represent colliding objects. It is an example of an elastic collision, where kinetic energy and momentum are conserved.
Step-by-step explanation:
The correct answer is a. Elastic collision, conservation of kinetic energy, and momentum.
In Newton's cradle, the swinging ball bearings represent the colliding objects. When a ball in the middle is lifted and released to strike the others, it collides with the first ball, which is then pushed away. The ball at the other end of the chain then rises and collides with the others, repeating the process.
During each collision, energy is transferred from one ball to the next, but the total energy in the system remains the same. This is an example of a perfectly elastic collision, where kinetic energy is conserved. The momentum of the system is also conserved, as the total momentum before the collision is equal to the total momentum after the collision.