🧾 Introduction
When an object moves in two dimensions (x & y), its motion is called motion in a plane.
It is described using vectors for displacement, velocity, and acceleration.
🔑 Key Topics
1️⃣ Vectors and Scalars
Scalar: Quantity with only magnitude (e.g., mass, speed, time)
Vector: Quantity with magnitude and direction (e.g., displacement, velocity, force)
2️⃣ Vector Addition
🔺 Triangle Law of Vector Addition
If two vectors A and B are represented by two sides of a triangle taken in order,
then the resultant vector R is given by the third side of the triangle taken in the opposite order.
🔷 Parallelogram Law of Vector Addition
If two vectors A and B acting simultaneously are represented by the two adjacent sides of a parallelogram drawn from a point, then their resultant R is represented by the diagonal of the parallelogram passing through that point.
🧮 Components of a Vector
3️⃣ Projectile Motion
Motion under gravity in 2D → parabolic path
Horizontal velocity is constant, vertical velocity changes due to gravity
Key Formulas:
4️⃣ Uniform Circular Motion
🎯 Why This Chapter Matters
Builds strong base for vector algebra, projectile motion, and rotational motion
Very important for NEET & JEE — several direct numericals come from this chapter
📝 Assignment Questions
1. State and prove the Parallelogram Law of Vector Addition.
2. Derive the equation for range of a projectile.
3. A car moves with a speed of 20 m/s on a circular track of radius 40 m. Find centripetal acceleration and force if mass of car is 800 kg.
🔑 Keywords:
Motion in a Plane Class 11, Parallelogram Law of Vector Addition, Triangle Law of Vector Addition, Resultant of Two Vectors, Vector Components Class 11, Projectile Motion Class 11, Time of Flight Formula, Maximum Height Formula, Horizontal Range Formula, Uniform Circular Motion Class 11, Centripetal Force Formula, Class 11 Physics Chapter 3 Notes, NEET Physics Motion in a Plane
