Avoid varying output on same amount of force applied to a Rigidbody2D.

So I have a Rigidbody2D (bot character) with a polygon collider on it. The shape of the collider resembles a pencil (somewhat). There's another Rigidbody2D with similar shape (the player's character). On collision of player with the bot, I'm applying force on the player.

Each time the force is applied, the behavior is different. Sometimes the force is quite low, and sometimes it is exactly what we want. Can't figure out how we could avoid this, and each time a consistent force is applied.