Question

Assertion-Newton's third law of motion is applicable only when bodies are in motion.
Reason-Newton's third law applies to all types of forces. e.g. gravitational, electric, or magnetic force, etc.,
A.Both assertion and reason are correct and reason is the correct explanation of assertion.
B.Both assertion and reason are correct but reason is not the correct explanation of assertion.
C.Assertion is correct but reason is incorrect.
D.Assertion is incorrect and Reason is correct.

Answer 1

Hint: Newton's third law of motion states that for an action there is an equal and opposite reaction. Both action and reaction act on two different objects. The third law of Newton is applicable for both a body at rest and for a body in motion.

Complete answer:
The assertion is incorrect because Newton's third law can act on a stationary body. Consider the act of tugging a rope.
Reason holds valid because there is a response pair for every action that operates on all forces.
Universal law of gravitation is $F = \dfrac{{G{m_1}{m_2}}}{{{r^2}}}$ both masses attract each other.
Coulomb’s law (electric force) $F = k\dfrac{{{q_1}{q_2}}}{{{r^2}}}$ both charges either attract or repel each other.
 Take two magnets and they either repel each other (opposite direction forces) or attract each other (opposite direction forces) depending on their orientation. In either case, the Third Law is obeyed.
So Newton's third law applies to all types of forces. e.g. gravitational, electric, or magnetic force, etc.

Hence option D) Assertion is incorrect and Reason is correct. Is the right option.

Note:
Assertion means a confident and forceful statement of fact or belief. Common examples of Newton's third law of motion are: A horse pulls a cart, a person walks on the ground, a hammer pushes a nail, magnets attract paper clips. In all these examples a force is exerted on one object and that force is exerted by another object