Mechanical weathering which is also referred to as the physical weathering occurs when a rock is broken down into smaller pieces. In this case, there will be a physical change of the rock but its composition will not change.
Some examples include ice freezing and expansion of the cracks in the rock, Smstrong winds that carrycpieces of sand which then sandblast surfaces, moving water which causes abrasion etc.
As the bird releases the drop there is no internal force which will drive it into circular path but it will fall on tangent of the arc at the point of release because it has a tangential velocity same as bird. Path will be parabola in vertical plane.
As the person is on circular arc constantly moving it will never meet that drop.
Explanation: Because of the way this water cycle has always circulated our planet, there is indeed a chance that the water in your glass is the same water that thirsty dinosaurs were drinking about 65 million years ago