0Kinematics in Physics
Kinematics is the branch of physics that studies:
Motion of objects without considering the cause of motion (force).
So in kinematics, we describe:
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How fast something moves
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How far it moves
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How its motion changes
We do NOT talk about forces (that comes in dynamics, like in the laws of Isaac Newton).
📌 Important Terms in Kinematics
1️⃣ Distance & Displacement
🔹 Distance
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Total path covered
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Scalar (no direction)
Example: Walk 5 m forward and 5 m back → Distance = 10 m
🔹 Displacement
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Shortest distance from start to end
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Vector (has direction)
Same example → Displacement = 0 m
2️⃣ Speed & Velocity
🔹 Speed
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Distance per time
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Scalar
Speed=DistanceTimeSpeed = \frac{Distance}{Time}Speed=TimeDistance
🔹 Velocity
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Displacement per time
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Vector (has direction)
Velocity=DisplacementTimeVelocity = \frac{Displacement}{Time}Velocity=TimeDisplacement
If a car moves east at 20 m/s → That is velocity.
3️⃣ Acceleration
Acceleration means:
Rate of change of velocity
a=v−uta = \frac{v - u}{t}a=tv−u
Where:
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uuu = initial velocity
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vvv = final velocity
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ttt = time
If velocity increases → Positive acceleration
If velocity decreases → Negative acceleration (retardation)
📘 Equations of Motion (Very Important)
These apply when acceleration is constant.
1️⃣ v=u+atv = u + atv=u+at
2️⃣ s=ut+12at2s = ut + \frac{1}{2}at^2s=ut+21at2
3️⃣ v2=u2+2asv^2 = u^2 + 2asv2=u2+2as
Where:
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sss = displacement
🎯 Types of Motion
🔹 Uniform Motion
Velocity is constant (no acceleration).
🔹 Non-Uniform Motion
Velocity changes (acceleration present).
📊 Graphs in Kinematics
1️⃣ Distance–Time Graph
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Straight line → constant speed
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Curved line → changing speed
2️⃣ Velocity–Time Graph
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Slope gives acceleration
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Area under graph gives displacement
🌍 Real-Life Example
If you drop a ball from a height:
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It accelerates due to gravity
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This motion was studied by Galileo Galilei
🔥 Simple Summary
Kinematics studies:
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Position
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Velocity
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Acceleration
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Motion equations
But NOT forces.
