Position-time Graph

According to NCERT Class 11, Chapter 3 (Motion in a Straight Line), a position-time graph plots displacement against time, and the slope of the tangent to this curve at any point gives the rate of change of position with time, which is by definition the instantaneous velocity. A steeper slope indicates faster motion, and a horizontal segment indicates rest. The option instantaneous acceleration is wrong because acceleration is the slope of a velocity-time graph, not a position-time graph. The option total distance covered is incorrect since distance relates to how the curve extends, not its slope. The option average speed is wrong because average speed involves total path over total time, represented by a chord rather than a tangent slope. Plausibility check: dimensionally, slope has units of position over time, that is metres per second, which is precisely the unit of velocity, confirming that the tangent slope of a position-time graph must represent instantaneous velocity.