In literature, a foil is a character who serves as a contrast to the protagonist or another important character. this contrast often to emphasize certain traits in the central character. how does laertes serve as a foil for hamlet in act iv, scene v, of hamlet?

To highlight a character's (usually the protagonist's) personality, the introduction of a foil is used. In Shakespeare's 'Hamlet', Laertes is Hamlet's foil. They were childhood friends but have completely opposite traits and behaviors: Hamlet is verbal, he ponders, and is driven by passionate inaction, Laertes is physical, blusters, and is driven by passionate action. 

In Act IV, scene V, we can see Laerts personality; he bursts and needs people to calm him down, whereas Hamlet would have stayed calm and think before acting. 

The answer would be analytical reasoning.