Activity: Understanding Uniform Motion Through Distance–Time Graphs (Class 7)
Topic
Graphical Method to Study Motion
Aim
To understand uniform motion using a distance–time graph.
Introduction
Motion is the change in position of an object with time.
A distance–time graph helps us understand how an object moves by showing the relationship between distance travelled and time taken.
In a distance–time graph:
• Time is represented on the X-axis.
• Distance is represented on the Y-axis.
Materials Required
• Graph paper
• Pencil
• Ruler
• Observation table
Activity 1: Uniform Motion
Plot the Graph
Draw two perpendicular axes.
Mark Time (s) on the X-axis.
Mark Distance (m) on the Y-axis.
Plot the points:
(0,0)
(5,10)
(10,20)
(15,30)
(20,40)
Join the points with a straight line.
Uniform motion
Conclusion
Uniform Motion
A body is said to be in uniform motion when it covers equal distances in equal intervals of time.
Characteristics:
✓ Speed remains constant.
✓ Distance–time graph is a straight line.
✓ Motion is non-accelerating.
Speed Calculation
Speed = Distance ÷ Time
= 40 m ÷ 20 s
= 2 m/s
The speed remains constant throughout the journey.
Non uniform motion
Activity 2: Non-Uniform Motion
Observation Table
Time (s)
0
5
10
15
20
Distance (m)
0
5
15
25
25
Plot the Graph
Plot the points:
• (0,0)
• (5,5)
• (10,15)
• (15,25)
• (20,25)
Join the points.
Observation
The graph is not a straight line with a constant slope.
Distance covered:
• 0–5 s → 5 m
• 5–10 s → 10 m
• 10–15 s → 10 m
• 15–20 s → 0 m
The object covers unequal distances in equal intervals of time.
During the last 5 seconds, the object does not move.
Conclusion
Non-Uniform Motion
A body is said to be in non-uniform motion when it covers unequal distances in equal intervals of time.
Characteristics:
✓ Speed changes continuously.
✓ Distance–time graph is not a straight line with uniform slope.
✓ Motion may be accelerating, decelerating, or include rest.
Real-Life Examples
Uniform Motion
• Escalator moving at constant speed
• Conveyor belt in a factory
• A train moving steadily on a straight track
Non-Uniform Motion
• A bicycle in city traffic
• A car moving through a crowded road
• A runner speeding up and slowing down
