Why does Cart B move faster than Cart A after the collision?

Explanation:

From the given scenario where Cart A stops after colliding with Cart B that was initially at rest and Cart B moves with a greater velocity than Cart A had, we can infer that Cart B must be lighter than Cart A.

In a collision, the conservation of momentum principle states that the total momentum of the system before the collision is equal to the total momentum of the system after the collision. Since Cart A stops and transfers all its momentum to Cart B and Cart B moves faster than Cart A initially did, this means Cart B has less mass. Therefore, the carts have unequal masses.

The most appropriate answer given the options would be (b) Carts B have unequal masses.