Question

A student unable to answer a question on Newton's laws of motion attempts to pull himself up by tugging on his hair. He will not succeed

• A. as the force exerted is small
• B. the frictional force while gripping, is small
• C. Newton’s law of inertia is not applicable to living beings
• D. as the internal force applied is to the system

Answer 1

The correct option is D

as the internal force applied is to the system

The explanation for the correct option $\left(D\right)$

1. Newton's Law of Inertia states that if a body is at rest, it will remain at rest unless it is acted upon by a force.
2. By applying an internal force, the momentum will not change. So he will not succeed.
3. Let the girl be the system, in this system action and reaction act on the same body so the results will be zero.
4. The girl is applying the internal force to her hair and as the internal force is acting, the momentum will not change.

The explanation for the incorrect options

Option $\left(A\right)$- The external force on the system is zero.

Option $\left(B\right)$-The frictional force is not small

Option $\left(C\right)$-Newton's law of inertia is applicable to living beings also.

Hence, the correct option is $\left(D\right)$.