Class 11 Physics Chapter 2 Motion in a Straight Line – Revision Notes

Chapter 2 of Class 11 Physics separates distance from displacement and speed from velocity before introducing the three kinematic equations that connect initial velocity, acceleration, and time. It also covers how slopes and areas on motion graphs represent velocity, acceleration, and displacement.

Last Updated: September 23, 2026

Key Terms

• Distance (scalar) vs Displacement (vector).
• Average speed = distance/time; Average velocity = displacement/time.
• Instantaneous velocity = dx/dt; Instantaneous acceleration = dv/dt.

Kinematic Equations

• v=u+at; x=ut+½at²; v²=u²+2ax.

Graphs

• Position-time slope = velocity.
• Velocity-time slope = acceleration; area = displacement.

Relative Velocity

• v_AB = v_A − v_B.

One-Line Summary

Motion in a straight line is described using position, displacement, velocity, and acceleration (including instantaneous, calculus-based definitions), governed by three kinematic equations for uniform acceleration.

Quick visual: a worked diagram from the full Solutions page, for reference.

Frequently Asked Questions

What is the difference between distance and displacement?
Distance is the total path length covered by an object regardless of direction, while displacement is the shortest straight-line distance from the initial to the final position along with direction, making displacement a vector quantity.

How do position-time and velocity-time graphs help analyse motion?
The slope of a position-time graph gives velocity at any instant, while the slope of a velocity-time graph gives acceleration, and the area under a velocity-time graph gives displacement.

Written by Satish

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