# Chapter 2 Notes | Physics 1st Year

## “Vectors and Equilibrium”

#### Index:

- Basic Concept of vectors.
- Vectors.
- Rectangular Coordinate system.
- Addition of Vectors.
- Resultant Vectors.
- Vectors Subtraction.
- Multiplication of a Vector with a Scalar.
- Unit Vector.
- Null Vector.
- Equal Vectors.
- Rectangular Components of a Vector.
- Determination of a Vector from its Rectangular Components.
- Position Vector.
- Vector Addition by Rectangular Components.
- Product of two Vectors.
- Vector or Cross Product.
- Torque.
- Equilibrium of Forces.
- First Condition of Equilibrium.
- Second Condition of Equilibrium.

#### Key Points:

- The arrangements of mutually perpendicular axes is called rectangular or Cartesian coordinate system.
- A scalar is a quantity that has magnitude only, whereas a vector is a quantity has both direction and magnitude.
- The Sum Vector of two or more vectors is called resultant vector.
- Graphically the vectors are added by drawing them to a common scale placing them head to tail, the vector connecting the tail of first to the head of the last vector is the resultant vector.
- Unit Vectors describe directions in space. A unit vector has a magnitude of 1 with no units.
- A vector of magnitude zero without any specific direction is called null vector
- The vector that describes the location of a particle with respect to the origin is called position vector.
- A body is said to be in equilibrium under the action of several forces if the body has zero transnational acceleration and angular acceleration.
- For a body to be in transnational equilibrium the vector sum of all the forces acting on the body must be zero.
- The torque is defined as the product of the force and the moment arm.
- The moment arm is the perpendicular distance from the axis of rotation to the direction of line of action of the force.
- For a body to be in rotational equilibrium,the sum of torques on the body about any axis must be equal to zero.

## 6 Comments

tahirrafiquenotes of physic 11th

nimzreally very nice

outstanding…..

tasawurpaper scheme of physics part 1 is not mentioned.

sunnyhttp://fsconline.info/physics-1st-year-2017-punjab-board-paper-scheme/

here you go bro !

fatimaThese key points are already given in book as summary……..

Not really helpful

ali atharSunny bro, can you share paper scheme of math and physics (federal board2017) as well?