Well, depending on which way you are pushing, it could be one of three forces.
If you are pushing along a table, then it is friction that is preventing the box from moving (or more accurately, static friction).
If you are pushing the box down into the table, then it is the normal force that is at work.
If you are pushing into the air, then it is gravity.
Buoyancy= ρgV, where ρ is the density of the liquid, g is the acceleration due to gravity, and V is the volume of water displaced.
frictional force
inersia
Simple answer: yes In order for you to stand, talk, move... ect objects must exert a force on you. For example if you are standing on the ground, the ground has to be pushing back at you, or you would just fall through. If an object doesn't exert the same force you exert on it, then you are moving the object.
The action force is your hand moving back. The reaction force is the ball moving the other way.
The answer is reaction. A simple example is you standing on the ground. You are not moving or accelerating (in our reference frame). You are pushing down against the ground with a force (the action) equal to your weight. The ground pushes back up (opposite direction) with an equal force (the reaction force).
Air fill the balloon and force it to expand but being a rubber base substance the balloon always in the state of pushing the air (that's why if you put a hole on a balloon it will "fly"). Air pushing is an action. Balloon pushing back is a reaction.
The idea of a reaction force comes from Newton's third law; "If object A exerts a force on object B ,then object B will exert an equal but opposite force back on A". In many problems some of the forces are considered as the "initiating" force or the applied force. When you consider a force as being applied, like a bulldoser pushing a rock, then the force which must act back , the rock pushing back on the doser, is called the reaction force. Sometimes you don't really have an initiating force but it still convienient to think of one force as the force of interest and the back force as the reaction force. There is no single formula for reaction force since it can apply to any force. For example, the earth attracts you with a force mg (your weight), then you can think of the reaction force as you attract the earth with a force -mg; equal but opposite.
static friction
gravity
The action is the finger pushing the nose. The reaction is the nose pushing back on the finger.
he is holding a stack of books on his back but he is not moving
If there was no friction, your foot would simply slide back as you tried to take steps, and you would go nowhere. In order for something to move, it has to have a force moving it. That force has to have leverage, or friction. For the force pushing a person forward, there is an equal force pushing backward on the ground or floor. You can observe this by placing round pencils under a board, stand on it, and try to step off in the perpendicular direction : the board will roll backward as you step forward.
Simple answer: yes In order for you to stand, talk, move... ect objects must exert a force on you. For example if you are standing on the ground, the ground has to be pushing back at you, or you would just fall through. If an object doesn't exert the same force you exert on it, then you are moving the object.
When an airplane is motionless on the tarmac, discounting any winds, there are two primary forces acting on it. First is the force of gravity pushing downwards, and secondly, there is the reactionary force pushing back upwards.
The action force is your hand moving back. The reaction force is the ball moving the other way.
The answer is reaction. A simple example is you standing on the ground. You are not moving or accelerating (in our reference frame). You are pushing down against the ground with a force (the action) equal to your weight. The ground pushes back up (opposite direction) with an equal force (the reaction force).
Possibly water resistance (drag)
Air fill the balloon and force it to expand but being a rubber base substance the balloon always in the state of pushing the air (that's why if you put a hole on a balloon it will "fly"). Air pushing is an action. Balloon pushing back is a reaction.
For every action there's an equal and opposite reaction. A clearer way of saying this may be: When you push on something it pushes back with a equal force. Think of pushing on a building. You apply a force on the building but it is pushing back with the same force, else it would move.