* Gravity: The primary force acting on the coin is gravity, which pulls it downwards.

* Initial Velocity: When you toss the coin, you give it an initial upward velocity.

* Deceleration: Gravity works against this initial upward velocity, causing the coin to slow down.

Think of it this way: The coin is fighting against gravity. As it goes up, gravity is constantly working to bring it back down. This results in the coin's upward velocity getting smaller and smaller until it reaches its highest point. At that point, its velocity momentarily becomes zero before it starts falling back down.