Cody's family went hiking along a stream in georgia and found a waterfall. at the bottom of the waterfall, they noticed many small pebbles with smooth edges on the bottom of the stream. if cody's family added more rocks to the stream at the bottom of the waterfall, what should they expect to happen to the size of the rocks?

They can expect the size of the rocks to get smaller as the time passes.

Explanation:

They can expect the size of the rocks to get smaller as the time passes.

This is so because the water falling from certain height under waterfall will exert mechanical impact on the rock due to the mass of the water. This will act as water hammer causing wear and tear to the rock particles and flowing them away with the stream of water. This hydraulic shock is generated when there is sudden stoppage in the motion of water. In sync with Newton's second law of motion, when the momentum of water is changed within a short course of time it creates a hammer like impact which has potential  of wear and tear when an object is continuously subjected to it.