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📘 Chapter 1: Motion and Measurement of Distances


 

🔹 1. Means of Transport (Past to Present)

Era Means of Transport
Ancient Walking, animals (bullocks, horses)
Early Tools Boats (shaped like fish), carts with wheels
Industrial Age Steam engine → trains, ships
Modern Age Cars, buses, bikes, airplanes, metros

Fact for UPSC: Transport evolution = key indicator of technological progress.

🔹 2. Measurement

Definition: Measurement is comparing an unknown quantity with a known fixed unit (standard unit).

✅ Ancient Units:

  • Cubit (elbow to fingertip)

  • Foot (length of a foot)

  • Angul (finger width)

  • Mutthi (fist)

✅ Standard Units:

  • SI Unit of Length: metre (m)

    • 1 m = 100 cm

    • 1 cm = 10 mm

    • 1 km = 1000 m

Why standard units? To avoid confusion — uniform, internationally accepted.

🔹 3. Correct Measurement of Length

  • Place the scale in direct contact with the object.

  • Don’t use broken or unclear scales.

  • Keep your eye level with the reading point to avoid parallax error.

🔹 4. Measuring Curved Lines

Straight scale won't work.
✅ Use a non-stretchable thread:

  1. Mark start point.

  2. Lay the thread along the curve.

  3. Measure thread length on a scale.

🔹 5. Motion & Its Types

Motion: A change in the position of an object over time.

✅ Types of Motion:

Type Description Examples
Rectilinear Moves in a straight line Bullet, car on straight road
Circular Moves in a circular path Fan blade, clock hands
Periodic Repeats after intervals Pendulum, swing, guitar string

📊 Summary Table

Concept Details
Measurement Comparison with a known unit
SI Unit of Length Metre (m)
1 km 1000 m
1 m 100 cm
Motion Change in position with time
Types of Motion Rectilinear, Circular, Periodic

🧠 Quick Revision Qs

  1. What is the SI unit of length? → Metre

  2. Name 2 ancient units of measurement. → Cubit, Foot

  3. What instrument is used to measure curved lines? → Thread

  4. Name a periodic motion example. → Pendulum

✅ Practice MCQs

  1. One of the early measures of length was:
    (a) Metre (b) Centimetre (c) Foot (d) Km

  2. Motion of moon around the earth shows:
    (a) Rectilinear (b) Circular (c) Periodic (d) Both b & c

  3. Cubit is a measure of length between:
    (a) End of arm and chin (b) Elbow to fingertips

  4. The SI unit of length is:
    (a) Km (b) cm (c) mm (d) m

📝 Homework:

  • Revise this concept.

  • Solve Level-1 & Level-2 MCQs from the book.

  • Mark difficult questions.