Retarded Motion and Displacement – Rankers Physics

Equations of Motion: Practice Problem & Solution

Assertion (A): If initial velocity is negative and acceleration is positive then motion is retarded (initially). Reason (R): If initial velocity is negative but acceleration is positive then displacement of a particle can never be positive.  
(1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
(2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(3) (A) is true but (R) is false
(4) Both (A) and (R) are false

Solution Explained:

To solve this problem, we apply the core principles of Equations of Motion. Understanding the underlying formula is key to arriving at the correct answer below:

Assertion (A) is true because if velocity and acceleration have opposite signs (negative velocity, positive acceleration), the object is slowing down (retarding) initially.


Reason (R) is false. An object with negative initial velocity and positive acceleration can eventually reverse direction and achieve positive displacement (e.g., if it starts at \(x=0\), it will eventually cross \(x=0\) and move to positive \(x\)).


Thus, (A) is true, (R) is false.

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