Question

Action and reaction can never balance out because

• A. they are equal but not opposite always.
• B. they are unequal in magnitude even though opposite in direction.
• C. though they are equal in magnitude and opposite in direction they act on different bodies.
• D. they are unequal in magnitudes.

Answer 1

The correct option is C though they are equal in magnitude and opposite in direction they act on different bodies.

Action and reaction forces are equal and opposite, but they are not balanced forces because they act on different objects so they don’t cancel each other out.
Example :

Here, FBD of a body resting on a surface is shown.
$mg$ is the weight of body which act downward and being applied by the earth (by the virtue of its mass) at the centre of gravity (COG) of the body.
Reaction of this weight will be one applied by the body due to its virtue of mass at the earth's COG.
While,
Normal force acting upward is another force which acts between contact surfaces and normal to surface.
Reaction of this normal force will be the one applied by the body on the surface in downward direction.
So we see, action - reaction pairs are of equal magnitude, of same nature, act simultaneously but their point of application remains on two different body.