So on a macro level or a physics frame of reference, the normal force (Based on my knowledge) exists to counter the force of gravity. What i am struggling to understand is....
How does the normal force exist? (i.e. what causes it to exist?)
FEEL FREE TO ALSO EXPLAIN IT ON A MICRO LEVEL (MOLECULAR LEVEL) BUT I WOULD ALSO APPRECIATE IF YOU EXPLAINED ITO ON A MACRO LEVEL
Does the normal force always equal the forces applied to it?
Can the normal force be overcome. (i.e. does the normal force have a threshold?)
E.G. SUPPOSE A BRICK IS PLACED ON A TABLE, MORE & MORE FORCE IS APPLIED TO THIS SAME BRICK, WHICH IN TURN EXERTS A FORCE ON THE TABLE, CAUSING THE BRICK TO BREAK THROUGH THE SURFACE OF THE TABLE. DOES THIS MEAN THE NORMAL FORCE HAS BEEN OVERCOME?
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- Thread Starter
Last edited by Paranoid_Glitch; 14-03-2016 at 07:36.
- 14-03-2016 07:35
- 15-03-2016 14:00
The normal force is the reaction on an object that lies perpendicular to the plane that the object is on. For example: Consider a book lying on a table. The weight of the book acts vertically downwards. The normal force (reaction) acts vertically upwards.
The normal force exists because if a force is applied to an object with no opposing force, it will accelerate (F = ma). For a book lying on a table, there are only two forces to consider: its weight acting down and the normal reaction. As the book is stationary, there cannot be any resultant force and so they cancel themselves out.
If a vertical force was applied to the book (with the intention of lifting it off the table), then if the vertical force is less than the weight of the book, then the normal reaction is the difference between the two. If the vertical force is equal to the weight of the book, the book is on the point of moving and the normal reaction will be zero.
Regarding your analogy with the brick, there would be other things to consider, e.g. the maximum pressure that could be applied to the table before it breaks. Until that occurs, the normal reaction would be equal to the sum of the vertical component of any force and the weight of the brick.
- 15-03-2016 16:16
The normal force acts in the direction that is perpendicular to the direction of possible motion of an object.
- 15-03-2016 16:18
- 15-03-2016 16:23
- 15-03-2016 16:29
(Original post by samb1234)
- 15-03-2016 16:37
I don't think that is a great way to define it - I inferred, and as may others, that you were talking about the possible direction of motion due to force itself. Also there are certain scenarios where the possible motion isn't horizontal - e.g. you might be drilling a well