The normal reaction is always equal to? (A) Weight (B) Tension (C) Both (D) None of these

1 Answer
Aug 14, 2017

I believe the answer is #"D"#.


Since a particular situation is not provided and the magnitude of the normal force (reaction) is circumstantial, you cannot say that it is always equal to any of the options provided.

For example, imagine that you have an object at rest on a horizontal surface, with #n=W#. Now imagine that you put your hand on top of the object and push down on it. The object does not move, which means that equilibrium is maintained, and as the weight of the object has not changed, the normal force as increased to accommodate the applied force. In that case, #n>W#

As for tension, simply saying "tension" is very nonspecific. For example, suppose an object is at rest on a horizontal surface with a rope attached to its side, which is being pulled such that there is tension #vecT# in the rope, but #vecF_"net"=0#. The normal force is perpendicular whereas the tension force is parallel. They cannot be equal.