Academia Aeternum
तमसो मा ज्योतिर्गमय
Wisdom · Knowledge · Eternity
NCERT | Class 11 | Physics
Everything moves. Kinematics is the mathematics of motion — the art of describing displacement, velocity and acceleration with precision.
Conceptual Framework
Quick Reference
| Quantity | Formula | Remarks |
|---|---|---|
| 1st Equation | \(v = u + at\) | Velocity–time relation |
| 2nd Equation | \(s = ut + \tfrac{1}{2}at^2\) | Displacement–time relation |
| 3rd Equation | \(v^2 = u^2 + 2as\) | Velocity–displacement relation |
| Average Velocity | \(\bar{v} = \dfrac{u+v}{2}\) | Only for uniform acceleration |
| nth Second | \(s_n = u + \tfrac{a}{2}(2n-1)\) | Displacement in nth second |
| Instantaneous Velocity | \(v = \lim_{\Delta t\to 0}\dfrac{\Delta x}{\Delta t}\) | Derivative definition |
| Relative Velocity | \(v_{AB} = v_A - v_B\) | Along a line |
Study Material
Exam-Ready Insights
Displacement ≠ Distance: displacement is a vector and can be negative; distance is always positive and ≥ |displacement|.
Velocity ≠ Speed: average speed = total distance/time; average velocity = total displacement/time.
The three kinematic equations apply ONLY to uniform (constant) acceleration.
Slope of x-t graph = velocity; slope of v-t graph = acceleration; area under v-t graph = displacement.
In free fall, all bodies (regardless of mass) experience the same acceleration g ≈ 9.8 m s⁻² (in vacuum).
If a ball is thrown up, at the highest point: v = 0, but a = g (downward) ≠ 0.
Distance covered in nth second = u + a(2n–1)/2 — a very frequently tested formula.
Competitive Exams
Motion in a Straight Line is tested across all major competitive examinations. Here are the most frequently tested topics:
Jump into the MCQ bank or the True–False quiz to gauge how well you've understood Motion in a Straight Line.
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