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NEET PHYSICSEasy

Given below are two statements: Assertion (A): A standing bus suddenly accelerates. If there was no friction between the feet of a passenger and the floor of the bus, the passenger would move back. Reason (R): In the absence of friction, the floor of the bus would slip forward under the feet of the passenger.

A

(A) is True but (R) is False.

B

(A) is False but (R) is True.

C

Both (A) and (R) are True and (R) is the correct explanation of (A).

D

Both (A) and (R) are True but (R) is not the correct explanation of (A).

Step-by-Step Solution

  1. Analyze the Physics (Inertia): According to Newton's First Law of Motion (Law of Inertia), a body at rest tends to remain at rest unless acted upon by an external force.
  2. Analyze the Forces: When the bus accelerates suddenly, the floor of the bus moves forward. If there is no friction between the feet and the floor, there is no horizontal external force to accelerate the passenger's body forward along with the bus.
  3. Evaluate Reason (R): Consequently, the floor of the bus slips forward under the feet of the passenger. This statement is True [1].
  4. Evaluate Assertion (A): Since the passenger remains at rest relative to the ground (due to inertia) while the bus moves forward, the passenger moves backward relative to the bus. This statement is True.
  5. Establish the Link: The backward motion relative to the bus occurs because the floor slips forward while the passenger stays stationary (due to lack of friction). Thus, the Reason correctly explains the Assertion. (Reference: NCERT Class 11, Physics Part I, Chapter 4: Laws of Motion, Section 4.4 explicitly discusses this scenario: "If there were no friction, we would remain where we were, while the floor of the bus would simply slip forward under our feet..." [1]).
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