 # CBSE Class 11 Physics Notes Chapter 4 Motion In A Plane

## What is Motion in a Plane?

Motion in a plane is referred to as a motion in 2 dimensions, for example, circular motion, projectile motion, etc. For analyzing a 2 Dimensional motion the reference will be made of an origin with two coordinate axes i.e X and Y.

### What is Scalar Quantities?

Scalar quantities are those physical qualities that can be specified completely by their magnitude alone. The examples of scalar quantities are mass, density, temperature, length, work, speed, etc.

### What is Vector Quantities?

Vector quantities are specified by both magnitude and direction. The examples of vector quantities are displacement, acceleration, momentum, velocity, torque, force, etc. The direction of any vector quantity is specified by a unit vector. Vectors lying in the same or parallel to the same plane are called coplanar vectors.

### Example of Motion in a Plane.

Projectile motion is one of the most common examples of motion in a plane. When an object moves in a circular path at a constant speed, then the object is said to be in a uniform circular motion.

Time Period

The time period of a uniform circular motion is the time taken by an object to complete one complete revolution in its circular path. To maintain an object in its uniform circular motion a radially inward acceleration must be maintained continuously, it is called as centripetal acceleration.

### Important Questions

1. State, for each of the following physical quantities, if it is a scalar or a vector:

volume, mass, speed, acceleration, density, number of moles, velocity, angular frequency, displacement, angular velocity.

1. Pick out the two scalar quantities in the following list:

force, angular momentum, work, current, linear momentum, electric field, average velocity, magnetic moment, relative velocity.

1. Pick out the only vector quantity in the following list:

Temperature, pressure, impulse, time, power, total path length, energy, gravitational potential, coefficient of friction, charge.

Students can clear all their concepts related to this unit by referring to the motion in a plane class 11 notes from the links given below: Motion In A Plane (2 Dimensional Motion) Visualizing Circular Motion In A Vertical Plane Projectile Motion Projectile Motion – Jumping off Cliffs