What's the best way to smoothly move a player backwards?

I’m currently making a boss fight and for an attack, the boss kicks the player to make the player get away from the boss. What’s the best way to make the player almost fling backwards?

There are many ways:

LinearVelocity

BasePart.AssemblyLinearVelocity

BasePart:ApplyImpulse

Oh cool. Could you give an example of each one of the stated?