LET'S EXPLORE (Page 16)
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On the map in Fig. 1.1 given on page 14 -
1. Mark the hospital.
2. What is the meaning of the blue-coloured areas?
3. Which is farther away from the railway station the school, the Nagar Panchayat or the public garden? Observe the map and identify the farther.1. Hospital: Located in the central part of the town map, situated between the railway station and the market, marked with a red cross symbol.
2. Blue-coloured areas: Represent water bodies like lakes, ponds, or rivers.
3. Farther location: The public garden (fenced green area on the far right) is the farthest away from the railway station compared to the school and Nagar Panchayat.
LET'S EXPLORE (Page 18)
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Draw a simple map of a school's playground (40 m length and 30 m width) on a scale of 1 cm = 10 m. Measure the diagonal and calculate the real length in metres.
- Dimensions on paper: Length = $40\text{ m} \div 10\text{ m/cm} = \mathbf{4\text{ cm}}$, Width = $30\text{ m} \div 10\text{ m/cm} = \mathbf{3\text{ cm}}$.
- Measurement of Diagonal on paper: Using Pythagoras theorem ($\sqrt{4^2 + 3^2} = \sqrt{16 + 9} = \sqrt{25}$) = 5 cm.
- Real length of the diagonal: $5\text{ cm} \times 10\text{ m/cm} =$ 50 metres. -
Consider the map of the small city again. Identify the correct and incorrect statements in the list below:
1. The market is north of the hospital.
2. The museum is southeast of the bank.
3. The railway station is northwest of the hospital.
4. The lake is northwest of the apartment blocks.Statement Ans 1. The market is north of the hospital. Incorrect (It is south of the hospital) 2. The museum is southeast of the bank. Correct 3. The railway station is northwest of the hospital. Correct 4. The lake is northwest of the apartment blocks. Incorrect (It is southwest of the apartment blocks)
LET'S EXPLORE (Page 24)
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Using the chessboard coordinate system, write down your move if you play black and respond with the same move as white (moving king's pawn two squares forward).
The move for black responding with the symmetrical opening move is from e7 to e5 (or d7 to d5 for queen's pawn).
LET'S EXPLORE (Page 30)
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Try to note down approximate values for the latitude and longitude of: (1) Mumbai, (2) Kolkata, (3) Singapore, (4) Paris.
1. Mumbai: $19^\circ\text{N}$ Latitude, $73^\circ\text{E}$ Longitude.
2. Kolkata: $22.5^\circ\text{N}$ Latitude, $88.4^\circ\text{E}$ Longitude.
3. Singapore: $1.3^\circ\text{N}$ Latitude, $103.8^\circ\text{E}$ Longitude.
4. Paris: $48.8^\circ\text{N}$ Latitude, $2.3^\circ\text{E}$ Longitude.
LET'S EXPLORE (Page 36)
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Two friends, one in Porbandar (Gujarat) and the other in Tinsukia (Assam), are speaking on the phone in late afternoon. The latter remarks that the sun has set in Assam and it is dark, while the former says it is still daylight in Gujarat. Explain why. Calculate the difference in local time between those two cities (assuming a longitude difference of 30°).
- Explanation: The Earth rotates from West to East. Because Assam is located in the eastern part of India, the Sun rises and sets earlier there than in Gujarat in the far west.
- Calculation of local time difference:
The Earth rotates $360^\circ$ in 24 hours $\implies 1^\circ = 4\text{ minutes}$.
$\text{Time difference} = 30^\circ \times 4\text{ minutes} = 120\text{ minutes} =$ 2 hours.
Local time in Tinsukia (Assam) is approximately 2 hours ahead of the local time in Porbandar (Gujarat).
LET'S EXPLORE (Page 38)
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Return to the two friends sitting in Gujarat and Assam. Use this example to explain the difference between local time and standard time.
- Local Time: The time determined by the position of the Sun at a specific meridian (midday Sun is 12:00 noon). The local time between Assam and Gujarat differs by about 2 hours.
- Standard Time: A single uniform time adopted for the whole country based on a central standard meridian ($82^\circ 30'\text{E}$ passing through Mirzapur, UP). Both friends set their clocks to the same Indian Standard Time (IST), avoiding confusion in train schedules, TV broadcasts, and business.
Questions, activities and projects (Page 42)
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1. Rohan is going on a trek. Which of the following will help him locate spots mentioned in his map?
Answer: C. Magnetic Compass (Directions)
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2. Name the physical object that represent the Earth.
A Globe is the true three-dimensional physical spherical model that represents the Earth.
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3. Why is it 5:30 pm in India when it is 12 pm or noon in London?
London is located on the Prime Meridian ($0^\circ$ longitude), while India's Standard Meridian is $82^\circ 30'\text{E}$.
- Since the Earth rotates $1^\circ$ in 4 minutes:
$82.5^\circ \times 4\text{ min} = 330\text{ minutes} = 5\text{ hours and } 30\text{ minutes}$.
- Since India lies to the east of Greenwich, Indian Standard Time (IST) is 5 hours and 30 minutes ahead of Greenwich Mean Time (GMT). -
4. Why do we need symbols and colours in the map?
Symbols and colours allow a vast amount of geographical and human information (like rivers, roads, railway tracks, towns, boundaries, mountains, schools) to be represented clearly in the limited space of a map without cluttering it.
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5. Mark the following statements as true or false; explain your answers with a sentence or two.
Statement Ans All parallels of latitude have the same length. False The length of a meridian of longitude is half of that of the Equator. True The South Pole has a latitude of 90°S. True In Assam, the local time and the IST are identical. False Lines separating the time zones are identical with longitude. False The Equator is also a parallel of latitude. True Explanations:
1. Parallels: False; the Equator is the largest circle and circles become progressively smaller towards the poles.
2. Meridian length: True; a meridian is a semicircle running from pole to pole, which is exactly half of the full circular circumference of the Equator.
3. South Pole: True; the poles are points located at an angular distance of $90^\circ$ from the Equator.
4. Assam time: False; IST is based on $82.5^\circ\text{E}$, while Assam lies around $95^\circ\text{E}$, so local time in Assam is about 50 minutes ahead of IST.
5. Time zone lines: False; time zone boundaries zigzag to follow political and national borders.
6. Equator: True; the Equator is the $0^\circ$ parallel of latitude. -
6. Two cities lie on the same longitude, one near the Equator and other closer to the North Pole. Compare and analyze how their climate and seasons would be different. Give reasons based on latitude.
- City near the Equator (Low Latitude): Receives direct, vertical rays of the Sun throughout the year, experiencing a hot, tropical (torrid) climate with very little seasonal temperature change.
- City closer to the North Pole (High Latitude): Receives slanting rays of the Sun spread over a large surface area, experiencing a cold (frigid/temperate) climate with distinct, severe winters and short cool summers.
Crossword & Numerical Questions (Page 44)
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7. Solve the crossword puzzle:
Clue Direction & Number Clue Description Ans Across 1 Lets you squeeze a huge area into your map SCALE Across 4 A convenient sphere GLOBE Across 5 The longest parallel of latitude EQUATOR Across 6 The place the Prime Meridian is attached to GREENWICH Across 8 So convenient to find your way MAP Across 10 A measure of the distance from the Equator LATITUDE Down 2 A measure of the distance from the Prime Meridian LONGITUDE Down 3 These two together allow us to locate a place COORDINATES Down 6 What latitudes and longitudes together create GRID Down 7 The time we all follow in India IST Down 9 On top of the world POLE Down 11 An abbreviation for a line across which the day and date change IDL -
8. Taking the scale to be 2.5 cm = 500 km (i.e. 1 cm = 200 km), calculate the real distance from the estuary of the Narmada River to the estuary of the Ganga River (measured distance on map ≈ 7.5 cm).
- Scale: $2.5\text{ cm} = 500\text{ km} \implies 1\text{ cm} = 200\text{ km}$.
- Map distance $\approx 7.5\text{ cm}$.
- $\text{Real distance} = 7.5 \times 200\text{ km} =$ 1500 km (approximately). -
10. Delhi's and Bengaluru's latitudes are 29°N and 13°N; their longitudes are almost the same, 77°E. How much will be the difference in local time between the two cities?
Since both cities lie on the same meridian of longitude (77°E), the difference in their local time is 0 minutes (No difference). Time depends entirely on longitude, not latitude.
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11. What is the difference between local time and standard time? Write an answer in 100 to 150 words.
Local Time is determined by the overhead position of the Sun at a specific longitude. When the Sun reaches its highest point in the sky at a given meridian, the local time is 12:00 noon. Because the Earth rotates $1^\circ$ every 4 minutes, every meridian of longitude has a different local time.
Standard Time is the uniform official time adopted by a country based on a centrally chosen meridian (Standard Meridian). For example, India uses $82^\circ 30'\text{E}$ as its standard meridian, known as Indian Standard Time (IST). Using standard time avoids confusion in transportation timetables, communication networks, and administrative schedules that would arise if every city followed its own local time.
