A block of mass 1kg moves on a rough surface with initial speed 4m/s. A retarding force F\=−0.8xN acts from x\=0.2m to x
Initial K=12×1×42=8J. As per NCERT Chapter 3, equations v=u+at, s=ut+½at², v²=u²+2as describe uniformly accelerated motion. Applying correct signs and units gives 8 J as the result, so option A is correct.
Ref: NCERT Class 11 Physics > Chapter 3: Motion in a Straight Line > Topic: Straight Line Motion - Practice Set0