In principle, when you fire a rifle, the recoil should push you backward. How big a push will it give

The answer is " because it is in the opposite direction of the bullet".

Explanation:

Given:

Using formula:

It recoils the velocity of the rifle  

Its negative sign displays the opposite direction of the rifle.

luster is not a good characteristic to use by itself because luster is the property of minerals that indicates how much the surface of a mineral reflects light. the luster of a mineral is affected by the brilliance of the light used to observe the mineral surface.