The magnitude of the normal force on the block is case 1 only.
Option a is correct
Since the normal force vector is determined by scaling the normal direction by the net surface contact force, the normal force vector is typically defined as the magnitude of the normal force, N, projected in the normal direction, n, by the net surface interaction force, T.
The numerical measure of a force's power is called its magnitude. For instance, let's say the force is 10 N in the direction of the east. "towards east" denotes direction, while "10" denotes the force's magnitude. Magnitude is, in essence, the "value" or "amount" of any physical quantity.
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