# Kinematics: A Complete Picture of Motion Without Causes

• crastinus
In summary, In special relativity, the speed of light is constant, while in quantum mechanics, the speed of light can change. Additionally, special relativity allows for the calculation of velocities and accelerations, while quantum mechanics cannot. Lastly, special relativity allows for the description of point trajectories, while quantum mechanics does not.
crastinus
So, if kinematics is the study of motion without reference to its causes (which is how it seems to be defined in many places), then here is my attempt to come up with a complete picture of motion without reference to its causes. This is just a summary to help me organize my thoughts (it is NOT meant to be a summary only of a first-year course on mechanics; it is meant to summarize everything in the study of motion without reference to its causes like forces).

Here's my "big picture":

1-, 2-, and 3-D position
1-, 2-, and 3-D motion

velocity as vector rate of change of position
acceleration as vector rate of change of velocity
jerk, snap, etc.

kinematic constraints
-holonomic
-non-holonomic

change of orientation of a body (here I don't know how this is generally described)
-rotation of body about a fixed axis

relative velocity and acceleration

point trajectories in a moving body (with velocity and/or acceleration)

motion of inertial reference frames
-rotation
-translation

accelerating reference frames (non-inertial reference frame)My first question is: Am I missing anything?

And my second question is: What is the best way to include here how motion at the relativistic scale and motion at the quantum scale are different from that of motion at the classical scale? In general, is there a way to give an outline that applies to motion at all scales?

crastinus said:
And my second question is: What is the best way to include here how motion at the relativistic scale and motion at the quantum scale are different from that of motion at the classical scale?

Learn Special Relativity; learn a bit of Quantum Mechanics.

yaa as we are advancing in physics we are coming to know about 4th d also as published in paper of Albert einstein

## 1. What is kinematics?

Kinematics is a branch of physics that studies the motion of objects without considering the causes of that motion, such as forces or energy. It focuses on describing the position, velocity, and acceleration of objects over time.

## 2. What are the three basic components of kinematics?

The three basic components of kinematics are position, velocity, and acceleration. Position refers to the location of an object in space, velocity is the rate of change of position, and acceleration is the rate of change of velocity.

## 3. How is kinematics different from dynamics?

Kinematics is the study of motion without considering the causes of that motion, while dynamics is the study of the causes of motion. Kinematics focuses on describing the motion of objects, while dynamics also takes into account the forces that affect that motion.

## 4. What is the difference between average and instantaneous velocity?

Average velocity is the total displacement of an object over a given time period, while instantaneous velocity is the velocity of an object at a specific moment in time. Average velocity is calculated by dividing the total displacement by the total time, while instantaneous velocity is calculated by finding the slope of the position-time graph at a specific point.

## 5. How does acceleration affect an object's motion?

Acceleration is the rate of change of an object's velocity. If an object has a positive acceleration, it is speeding up, while a negative acceleration means it is slowing down. Acceleration also affects the direction of an object's motion, as a change in direction is also considered a change in velocity, and therefore, acceleration.

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