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Grade 7 STEM

Motion, Speed & Simple Pendulum Lab

Interactive CBSE Class 7 Science laboratory (NCERT Chapter 9). Experiment with uniform and non-uniform motion, plot live Distance–Time (s–t) graphs, calculate speed with unit conversions, and verify the physics of the simple pendulum.

CBSE Grade 7 NCERT Ch 9 Physics Lab
Physical Motion Track (Drag vehicle or watch motion)
0.0 m/s (0.0 km/h) Distance: 0.0 m Time: 0.0 s
🚗
Distance–Time (s–t) Graph Ready
Graph Slope & Speed Analysis
NCERT Core Principle:
Speed = Slope of (s–t) Graph
Speed = (s2 − s1) / (t2 − t1)
Change in Distance (Δs): 0.0 m
Change in Time (Δt): 0.0 s
Computed Slope (Speed): 0.0 m/s
Speedometer Reading: 0.0 km/h
Uniform Motion
The graph is a straight sloping line. This indicates the object is covering equal distances in equal intervals of time (constant speed).
Oscillating Simple Pendulum At Mean Position
Extreme A ← Mean (O) → Extreme B
Pendulum Controls & Stopwatch
NCERT Table 9.2: Period of 20 Swings
Swings
0 / 20
Time (20 Swings)
0.0 s
Period (T)
—
Formula: T = (Time for 20 Oscillations) / 20
Key Scientific Discovery:
Galileo Galilei discovered that the time period of a simple pendulum depends only on its length (l), regardless of how heavy the bob is or how wide the release angle is!
T = 2π √(l / g) ≈ 2 × 3.1416 × √(0.8 / 9.8) = 1.79 s
Speed, Distance & Time Solver
Step-by-Step Calculation:
Speed = Distance / Time
Speed = 100 m / 10 s = 10 m/s
Final Answer: 10.0 m/s (36.0 km/h)
km/h ↔ m/s Unit Converter (5/18 Rule)
NCERT Derivation:
1 km = 1000 m and 1 hour = 3600 seconds.
1 km/h = 1000 m / 3600 s = 5 / 18 m/s.
• To convert km/h → m/s, multiply by 5 / 18.
• To convert m/s → km/h, multiply by 18 / 5.
Fascinating Real-World Speeds
Entity Speed (m/s) Speed (km/h)
Garden Snail 0.001 m/s 0.005 km/h
Human Walking 1.4 m/s 5.0 km/h
Usain Bolt (Olympic Sprint) 10.4 m/s 37.6 km/h
Cheetah (Fastest Land Animal) 31.0 m/s 112.0 km/h
Peregrine Falcon (Diving) 89.0 m/s 320.0 km/h
Commercial Airplane 250.0 m/s 900.0 km/h
Speed of Sound in Air 343.0 m/s 1,235.0 km/h
CBSE Class 7 Science: Chapter 9 Summary Notes
1. Slow or Fast & Speed Definition

An object that covers a higher distance in a given time moves faster. The distance moved by an object in a unit of time is called its Speed:

Speed = Total Distance Covered / Total Time Taken
  • Uniform Motion: An object moving along a straight line with a constant speed.
  • Non-Uniform Motion: If the speed of an object moving along a straight line keeps changing.
2. Measurement of Time & Periodic Events

Natural periodic cycles were traditionally used to count time (sunrise to sunrise = 1 day, new moon to new moon = 1 month, seasons = 1 year).

  • Sundial: Uses the shadow cast by the sun (e.g., Jantar Mantar, New Delhi).
  • Water & Sand Clocks: Rely on the fixed rate of flow of water or sand.
  • Quartz Clocks: Modern clocks and watches use electronic periodic oscillations of a quartz crystal for high precision.
3. The Simple Pendulum Terms

Consists of a small metallic ball (called the bob) suspended from a rigid stand by a taut string.

  • Oscillatory Motion: The to-and-fro motion of a simple pendulum is an example of periodic or oscillatory motion.
  • One Complete Oscillation: When the bob moves from its central mean position O to extreme A, then to extreme B, and back to O.
  • Time Period (T): The time taken by the pendulum to complete one full oscillation.
4. Speedometer vs. Odometer

Instruments mounted on the dashboard of vehicles:

  • Speedometer: Records the instantaneous speed of the vehicle directly in km/h.
  • Odometer: Records the total distance travelled by the vehicle in kilometres (km).
  • Distance–Time Graph Slope: The steeper the slope of a distance-time line, the higher the speed of the vehicle.