Fundamental Physics Quick Revision 11th Standard 101-2a

101-2a

This part deals with the essentials of the three main kinematic parameters and the equations pertaining to motion.

The world, and everything in it, moves. Even seemingly stationary things, such as a roadway, move with Earth’s rotation, Earth’s orbit around the Sun, the Sun’s or- bit around the center of the Milky Way galaxy, and that galaxy’s migration relative to other galaxies. The classification and comparison of motions (called kinematics) is often challenging. What exactly do you measure, and how do you compare?

Before we attempt an answer, we shall examine some general properties of motion that is restricted in three ways.

1. The motion is along a straight line only. The line may be vertical, horizontal, or slanted, but it must be straight. 


2. Forces(pushes and pulls)cause motion. In this chapter we discuss only the motion itself and changes in the motion. Does the moving object speed up, slow down, stop, or reverse direction? If the motion does change, how is time involved in the change? 


3. The moving object is either a particle (by which we mean a point-like object such as an electron) or an object that moves like a particle (such that every portion moves in the same direction and at the same rate). A stiff pig slipping down a straight playground slide might be considered to be moving like a par- ticle; however, a tumbling tumbleweed would not. 


The three main kinematic parameters are:

Parameter            Standard unit of measure

Displacement                         m
Velocity                                 m/s
Acceleration                          m/s²

As you may well know, all three above quantities are vector quantities, meaning that they have both magnitude and direction.

It is also to be noted that all three of these quantities are incremental differentials of the same physical quantity, displacement, with respect to time.

To elaborate,

Displacement is the shortest distance between two points. Its magnitude is in meters, and relative direction can be either along the positive direction on the Cartesian plane or along the negative direction on the Cartesian plane.

It's variation, i.e differential, with respect to time renders the result we call velocity.
The rate of change of displacement with respect to time is therefore what is known as velocity.

The same directional parameters as those of the displacement that determined it, will play a part in determining the direction of the velocity.

The rate of change of velocity, following from the case of velocity will also derive it's direction from the former. This is acceleration.

There are 4 fundamental equations of motion connecting the three quantities and time:

Where v is final velocity, u is initial velocity, a is acceleration, s is displacement and t is time