# Chapter 3 Notes | Physics 1st Year

## “Motion and Force”

#### Index:

- Motion
- Displacement
- Velocity
- Average Velocity
- Instantaneous Velocity
- Acceleration
- Average Acceleration
- Instantaneous Acceleration
- Uniform Acceleration
- Review of Equations of Uniformly Accelerated Motion
- Acceleration due to Gravity
- Newton’s Laws of Motion
- Momentum
- Impulse
- Isolated System
- Laws of Conservation of Momentum
- Collision
- Elastic Collision in one Dimension
- Force due to Water Flow
- Momentum and Explosive Forces
- Rocket Propulsion
- Projectile Motion
- Applications to Ballistic Missiles

#### Key Points:

- Displacement is the change in the position of a body from its initial position to its final position.
- Average velocity is the average rate at which displacement vector changes with time.
- Instantaneous velocity is the velocity at a particular instant of time. When the time interval, over which the average velocity is measured, approaches zero, the average velocity becomes equal; to the instantaneous velocity at that instant.
- Average acceleration is the ratio of the change in velocity Δv that occurs within time interval Δt to that time interval.
- Instantaneous acceleration is the acceleration at a particular instant of time. It is the value obtained from the average acceleration as time interval Δt is made smaller and smaller, approaching zero
- The slope of velocity-time graph at any instant represents the instantaneous acceleration at that time.
- The area between velocity-time graph and the time axis is numerically equal to the distance covered by the object.
- Freely falling is a body moving under the influence of gravity alone.
- Newton’s Law of Motion
- 1st Law: The velocity Of an Object will be content at any face on it is zero
- 2nd Law: an object gains momentum in the direction of applied force, and the rate of change of momentum is proportional to the magnitude of force.
- 3rd Law: when two objects interact, they exert equal and opposite force on each other for the same length of time, and so receive equal and opposite impulses.

- The momentum of an object is the product of its mass and velocity.
- The impulse provided by a force is the product of force and time for which it acts. It equals change in momentum of the object.
- For any isolated system, the total momentum remains constant. The momentum of all bodies in a system and up to the same total momentum at all time.
- Elastic Collisions Conserve Both momentum and kinetic Energy. In elastic Collision, Some of the energy is transferred by heating and dissipation forces such as friction, air resistance and viscosity, so increasing the internal energy of nearby objects.

## 7 Comments

danishthese physics notes are very help ful for me

amna29 page is missing

sadaf subhanio god..jo page mjhy chchye tha wo toh yahan pr b missing hy aur problem b usi article me thi

FSc OnlineWhich page are you talking about?

Shafeeq29 is missing

sadaf subhanipage no 29

in which projectile motion is explain

that is missing and i wnt that one

rao asif wajdaanVrery good but it should be in MS DOC files too