# Motion Along a Straight Line Index

## Free fall acceleration

Free fall acceleration: If you throw something vertically upward and could somehow eliminate or ignore the effect of drag and air on the object , Then the object accelerates constantly when it goes up and falls down , This is called free fall. If something falls freely under the effect of earth’s gravity without any effect of air then the phenomenon is called free fall. While the free fall , no matter how big , small or weighty the object is ,  every object feel the same constant acceleration , the constant acceleration during free fall...

## Constant acceleration & Constant acceleration equations Constant acceleration: Acceleration is said to be constant when the rate of change of velocity of an object is constant. In many types of motion , The acceleration is either constant or approximately constant , For example when you drive a car and accelerate it , you accelerate it in almost constant rate. When you are in a constant acceleration your Position-Time , Velocity-Time and Acceleration-Time curve looks like this:   Constant acceleration equations: Constant acceleration or deceleration is so common in Physics and in life that a...

## Acceleration

Acceleration: When the velocity of a particle changes then it is said to undergo acceleration. Acceleration is a vector quantity. When velocity of the object increases then the acceleration is positive and when velocity decreases the acceleration is negative and is called deceleration. Mathematically, For an motion along an axis: Average acceleration = Where , “v2″ is the velocity at time “t2″ and “v1″ is the velocity at time “t1″. And the limiting value of the average acceleration as tends...

## Instantaneous velocity and speed.

Instantaneous velocity: Beside instantaneous velocity , average velocity is a way of defining how fast a body is moving.But  average velocity is only the average of the velocity of body over a given time interval ,  and not the exact measure of velocity of a body at an instant. The exact measure of velocity of a body at an instant or over a very-very-very short time interval is known as instantaneous velocity. Mathematically instantaneous velocity of an object is the limiting value  of average velocity as tends towards...

## Average velocity and Average speed.

Average velocity: Average velocity is the measure of the average change of position of an object in any given time interval. Mathematically, Average velocity = Where , = Total change in position , = total time interval. = position of the object at two different time and = Different time. Average velocity does not depend on the actual path followed by the object , It only depends on the initial and final position of the object in a time period. If we draw a graph “x” versus “t”  for the motion of an object; where ,...

## Standards of Measurement: Length , Mass and Time.

The laws of physics are expressed as mathematical relationships among physical quantities. Most of these quantities are derived quantities, or they can be expressed as combination of some basic quantities. There are mainly three quantities in physics or mechanics, Length , Mass and Time. To do calculations and analysis in physics a standard is established for each of these three quantities. Which are as follows: Length: The history of unit of length dates a long back. In A.D. 1120 the king of England decided that the standard of length in his...

## Position and Displacement. What is Position? Position of an object is its location. In science, to find the position of an object we take a reference point or already known location and compare the location of two. We regard a place as reference point as the origin and find the distance of the object from the origin to find it’s  location as shown in figure below. in above Example there are two Objects whose position are x=-2m and x=3 m. Or the first one is 2m away from origin in negative direction and second one is 3 m away from origin in positive...