NEET · Physics
Own official Unit 2 at unit level while giving focused depth to one-dimensional motion, graphs and uniformly accelerated motion; Motion in Plane owns the vector/projectile/circular-motion child depth.
In short
Kinematics describes motion without first asking what force caused it. For one-dimensional NEET problems, define the axis and sign convention, identify whether acceleration is constant, then choose graph relationships or the constant-acceleration equations only when their conditions are satisfied.
Subject faculty
Also in Physics: Kumar Gandharva Saxena
Choose a frame of reference and a positive direction. Position and displacement are signed in one dimension; distance is path length. Average velocity is displacement divided by elapsed time, whereas average speed uses total distance. Instantaneous velocity and acceleration describe local rates of change.
The slope of a position-time graph gives velocity. The slope of a velocity-time graph gives acceleration. The signed area under a velocity-time graph gives displacement. Students should inspect axes and signs before treating every area as distance.
The familiar kinematic equations are not universal motion equations. They require constant acceleration over the interval. If acceleration changes with time or position, use the appropriate graph or calculus relationship if it is inside the expected level; do not force constant-acceleration formulas.
Official Unit 2 also includes scalars/vectors, vector operations, relative velocity, Motion in Plane, projectile motion and uniform circular motion. Those two-dimensional components are owned in depth by /neet/physics/motion-in-plane; this Kinematics page remains the unit owner and one-dimensional foundation.
Velocity definition: v_avg = Δx/Δt; instantaneous v = dx/dt. x in m, t in s, velocity in m s^-1; vector/sign-bearing in 1D. Average uses displacement, not distance.
Velocity definition
Use when — x in m, t in s, velocity in m s^-1; vector/sign-bearing in 1D. Average uses displacement, not distance.
Acceleration: a_avg = Δv/Δt; instantaneous a = dv/dt. m s^-2. Sign depends on axis choice; negative acceleration does not always mean slowing down.
Acceleration
Use when — m s^-2. Sign depends on axis choice; negative acceleration does not always mean slowing down.
Constant acceleration 1: v = u + at. Valid only for constant acceleration over the interval. u,v m s^-1; a m s^-2; t s.
Constant acceleration 1
Use when — Valid only for constant acceleration over the interval. u,v m s^-1; a m s^-2; t s.
Constant acceleration 2: s = ut + (1/2)at^2. Constant acceleration; s is signed displacement from the chosen origin/reference.
Constant acceleration 2
Use when — Constant acceleration; s is signed displacement from the chosen origin/reference.
Constant acceleration 3: v^2 = u^2 + 2as. Constant acceleration. Useful when time is not needed or given.
Constant acceleration 3
Use when — Constant acceleration. Useful when time is not needed or given.
Average velocity under constant acceleration: v_avg = (u+v)/2. Only for constant acceleration in one dimension over the interval.
Average velocity under constant acceleration
Use when — Only for constant acceleration in one dimension over the interval.
Concept being tested: Constant-acceleration motion
Prompt: A car moves in a straight line with initial velocity 5 m s^-1 and constant acceleration 2 m s^-2 for 4 s. Find final velocity and displacement.
Decisive condition: Acceleration is explicitly constant, so the standard kinematic equations apply.
Method choice: Use v=u+at and s=ut+(1/2)at^2.
Reasoning/calculation: v=5+2×4=13 m s^-1; s=5×4 + 0.5×2×16 = 36 m.
Unit/sign/condition check: Units are m s^-1 and m. Positive signs follow the chosen forward direction.
PI if answered incorrectly: Execution Error if a wrong sign or unit is used; Decision / Selection Error if constant-acceleration equations are used without checking the condition.
Using v = u + at when acceleration changes
Decision / selection errorWhy it happens
Preparation Intelligence classification: Decision / Selection Error.
How it is corrected
Verify constant acceleration first.
Treating negative acceleration as automatically slowing down
Knowledge gapWhy it happens
Preparation Intelligence classification: Knowledge Gap.
How it is corrected
Compare velocity and acceleration signs.
Using area under a velocity-time graph as distance without sign handling
Execution errorWhy it happens
Preparation Intelligence classification: Execution Error.
How it is corrected
Signed area gives displacement; distance needs total path treatment.
Confusing average speed and average velocity
Recall gapWhy it happens
Preparation Intelligence classification: Recall Gap.
How it is corrected
Check distance vs displacement in the numerator.
FAQ
Straight answers about how Rank Sarthi fits into serious exam preparation.
When acceleration is constant over the interval.
Signed displacement.
No. Speed decreases when velocity and acceleration are opposite in sign/direction.
Official scope is taken from the NEET (UG) 2026 syllabus and official NTA documents; concept structure follows current NCERT contents. No performance, weightage or question-frequency data is asserted.
