This is not an idiom. It is an expression whose meaning may be deduced from its component parts, unlike an idiom, whose meaning cannot be deduced from its component parts. It means having extremely limited options while being forced to act, like a person who is cornered in a fight.
Meaning being in desperate straits
Yes, "up against the wall" is an idiom meaning to be in a difficult or challenging situation with limited options or room to maneuver. It is often used metaphorically to convey a sense of feeling trapped or pressured.
Up against it, back against the wall, up against the wall is not an enviable position to be in. It means you are not in a good spot, you are in trouble with forces closing in on you. Usually used at work to mean that there is a lot of work to do and it is likely very difficult to achieve a goal.
Back Against the Wall was created in 2005.
Back Up Against the Wall was created in 1973-02.
The inability of students to think up their own sentences makes me bang my head against the wall.
The term "your back is against the wall" means that you have reached a point where you have no other options. When your back is against the wall you have no other course than to either give up or move forward and face what has you backed against the wall. Since this question was put into the Christian category I will answer it as a Christian. There will be times in your life that things will go wrong. It will seem that all things are against you and you have your back against the wall with no way out. I fully believe that Satan makes you feel like you have been abandoned and unloved so that you will give up. This is a lie. God will never abandon you. I have had my back against the wall countless times in my life and each time God has saved me. When my back is against the wall it gives me time to pray to God that He will help and deliver me. He has never failed me. Also when your back is against the wall it gives you something to push off from. When your back is against the wall, Look up!
The equal and opposite reaction is the wall pushing back against you. When you hit the wall with a stick, the force you exert on the wall is transferred to you through the stick, causing the wall to push back with an equal force. The stick simply transmits this force between you and the wall.
to bang your head against a brick wall
According to Newton's third law, the wall will push back against you with an equal force in the opposite direction.
If you lean on a wall, the reaction would depend on the stability and strength of the wall. In general, the wall will support your weight and you will feel leaning against it. If the wall is unstable or weak, it may not hold your weight and could potentially collapse.
It's a way of showing you're very frustrated. The image is of you being so upset that you're banging your head on the wall because you can't think of anything else to do.