Question

When you flick a coin so that it slides across a table, it slows down.

Answer 1

Well it depends on the coin and the tables material, a table is a bit too broad, either what i know could be friction force between the table and the coin or air resistance force. not sure about gravity force

Sorry not sure 

Answer 2

Gravity is acting on every object, but friction between the two objects is the resisting force causing the coin to slow it's horizontal motion across the table surface.