2Cu + S ~~~> Cu2S Copper (C) reacts with sulfur (S) to form copper sulfide as shown in the equation. A scientist adds 12.7 grams of Cu to 3.2 grams of S to start the reaction.
The forces involved in a collision are equal in size and directed in the opposite direction, and they accelerate both objects. Each object accelerates equally in collisions with things of equal mass.
