system
Given the following post, respond as if you're commenting on Reddit:
human
When two balls are released on a Newton's Cradle, why is the momentum transferred to the two at the end and not just one (giving it a greater speed)?
gpt
It needs to conserve momentum and kinetic energy.

    p = mv
    ek = 1/2 mv^2

As you adjust the mass and velocity the momentum and kinetic energy change by different amounts. Because they must be equal on both sides of the cradle, the only solution is that the same amount of mass moves at the same speed.