When does a normal force not exist on an object?

[Perseverance7779311]

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Hey guys, could you please tell me when does a normal force not exist on an object? Thank you.

 

[Vybe]

Normal force is present when an object is sitting on a plane or floor of some sort. It is perpendicular to the horizontal of that particular plane.

Newton's 3rd law of motion

 

[Teleologist]

When there are no forces involved, then there is no normal force. Normal force is a reaction force.

 

[Perseverance7779311]

@Vybe, thank you! Let me just ask you this, is an objects always sitting either sitting on a plane or on a floor?

 

[Perseverance7779311]

@Teleologist. thank you!

 

[Vybe]

@Vybe, thank you! Let me just ask you this, is an objects always sitting either sitting on a plane or on a floor?

Yes because normal force is only due to an opposite force. So if there is a box on the floor (flat) the force pointing down is f=mg, which is also equal to the normal force pointing up(opposite direction).

Every action has an equal and opposite reaction.

 

[DrknoSDN]

@Vybe, thank you! Let me just ask you this, is an objects always sitting either sitting on a plane or on a floor?

Yes because normal force is only due to an opposite force. So if there is a box on the floor (flat) the force pointing down is f=mg, which is also equal to the normal force pointing up(opposite direction).

Every action has an equal and opposite reaction.

That is not accurate.
The normal force can exist even if the surface is not horizontal (or the floor). A ball rolling down a ramp still experiences a normal force that is perpendicular to the slope of the ramp.
Normal force can also exist on a curve. A ball rolling in a halfpipe experiences a normal force that is always pointed towards the center of the circle. (also motorcycle cage of death)

Normal force can even exist without gravity. Spinning Spaceship that simulates gravity from centrifugal effects would cause you to experiences a normal force towards the center of rotation. (http://en.wikipedia.org/wiki/Rotating_wheel_space_station)

The normal force just prevents solid bodies from moving through each other.

 

[Perseverance7779311]

@Vybe and @DrknoSDN, thank you!

 

[Vybe]

That is not accurate.
The normal force can exist even if the surface is not horizontal (or the floor). A ball rolling down a ramp still experiences a normal force that is perpendicular to the slope of the ramp.
Normal force can also exist on a curve. A ball rolling in a halfpipe experiences a normal force that is always pointed towards the center of the circle. (also motorcycle cage of death)

Normal force can even exist without gravity. Spinning Spaceship that simulates gravity from centrifugal effects would cause you to experiences a normal force towards the center of rotation. (http://en.wikipedia.org/wiki/Rotating_wheel_space_station)

The normal force just prevents solid bodies from moving through each other.

I used the flat surface as an example, not as the only way there is a normal force.