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TRANSLATIONAL & ROTATIONAL
MOTION
Lesson2
Motion is the observable
change in position of a
body with respect to a
reference point.
TYPES OF MOTION
Motion where an object moves
from one place to another.
TRANSLATIONAL
Motion where an object spins
or rotates around an axis.
ROTATIONAL
TRANSLATIONAL
• Translational motion happens when an
object moves from one place to
another.
• All parts of the object move in the
same direction.
EXAMPLES:
• Walking
• Running
• Moving train
• Sliding cabinet
Linear Quantities
• Displacement
• Velocity
• Acceleration
Translational Motion:
Moving in a Straight Line
● Occurs when an object moves in
a straight line
● Described by linear quantities:
● Linear displacement
● Linear velocity
● Linear acceleration
● Example: A car moving down a
highway
• Linear displacement is the change in position of
an object along a straight path.
Scenario:
A car moves 100m in a straight line from Point A to Point B.
Starting Point (A): 0 meters
Ending Point (B): 100 meters
Direction: East
Linear Displacement = Final Position – Initial Position
Ans.: Linear Displacement=100m−0m=100meters East
Linear quantities:
Displacement Δx: Δx=xf−xi
where Δx is displacement,
xf is the final position, and
xi is the initial position.
• Linear velocity - how fast and in what direction
an object is moving along a straight path.
Linear quantities:
• Linear acceleration - measures how the linear
velocity of an object changes with time.
Linear quantities:
ROTATIONAL
• Rotational motion happens when an
object spins around an axis.
• The center point is called the axis of
rotation.
• “Turning or spinning around a center”
EXAMPLES:
• Electric fan
• Ferris wheel
• Spinning top
• Bicycle wheel
Angular Quantities
• Angular displacement
• Angular velocity
• Angular acceleration
Angular Quantities
Linear Displacement vs.
Angular Displacement
● Linear Displacement: Total distance moved in a straight
line
● Angular Displacement: Total angle rotated around an axis
Compare and contrast
Angular displacement (θ) is the angle (in radians) through which an
object moves on a circular path. One complete revolution around a
circle equals 360 degrees, which is equivalent to 2𝜋 radian
Angular displacement of a complete circle=2π radians or 360∘
Compare and contrast
Angular displacement
Formula: θ = (Number of Rotations)(2π)
Where:
𝜃= angular displacement (radians)
2𝜋radians = 1 complete rotation
Angular Displacement
Example: A Ferris wheel makes 4 complete rotations. Find its angular
displacement.
θ = n(2π)
𝜃 = 4 2𝜋
𝜃 = 8𝜋 radians
Linear Velocity vs. Angular Velocity
● Linear Velocity: Speed in a
straight line
● Measured in meters per
second (m/s)
● Angular Velocity: how fast
something is rotating or
spinning around a point or
axis.
Compare and contrast
Formula:
Example:
If a wheel spins 2 full circles in 4 seconds. Find the Velocity
•One full circle = 2π radians
•So, 2 full circles = 4π radians
•Time = 4 seconds
Angular Velocity
Formula:
1
or π rad/ sec
Linear Acceleration vs. Angular
Acceleration
Linear Acceleration: Rate of change of linear velocity
Angular Acceleration: Rate of change of angular velocity
● Both describe how quickly speed is changing
Compare and contrast translational and rotational motion
Angular Acceleration
Compare and contrast translational and rotational
motion
Example: If a wheel’s angular velocity changes
from 2π rad/s to 6π rad/s in 2 seconds. Find the
angular acceleration.
Compare and contrast translational and rotational
motion
Angular Acceleration
6π rad/s - 2π rad/s
2 seconds
= 2 rad/s2
=
COMPARISON
Translational Motion Rotational Motion
Moves from one place to
another
Spins around an axis
Uses linear quantities Uses angular quantities
Example: moving car Example: spinning fan
• Both involve movement.
• Both can change speed.
• Both are important in daily life.
SIMILARITIES
Remember!
ROLLING MOTION
• Rolling objects show two motions at the same
time:
• Translational Motion → moving forward
• Rotational Motion → spinning around an axis
Examples
• Bicycle wheel
• Toy car
• Bowling ball
Key Idea
Objects like wheels and balls move and rotate simultaneously.
Main Linear Quantities
• Displacement → distance moved
• Velocity → speed with direction
• Acceleration → change in speed
Examples
• Walking forward - Car moving on a road
• Running athlete
Linear quantities describe straight-line motion.
Main Angular Quantities
• Angular displacement → amount of turning
• Angular velocity → speed of rotation
• Angular acceleration → change in rotational speed
Examples
• Spinning fan Ferris wheel Rotating gear
Angular quantities describe rotational or circular motion.
Example Analysis
In basketball shooting:
• Arms rotate during the shot.
• The player may jump forward translationally.
• The ball rotates while moving through the air.
Examples
• Cycling Dancing
• Basketball shooting Gymnastics
Many physical activities combine translational and rotational motion.
APPLICATIONS IN
REAL LIFE
Linear and angular quantities are
important in:
• transportation
• sports
• machines
• exercise
SUMMARY EXAMPLES
• Bicycle wheels rotate while
moving forward.
• Washing machines spin clothes.
• Basketballs rotate while
traveling.
• Importance
⚬ Understanding motion helps:
■ improve machine efficiency
■ explain movement in everyday life
■ understand sports performance