Question 1

1. High-precision GPS stations on the Indo-Australian Plate show it is moving northward at a velocity of v = 2.5 cm/year. Calculate the total distance d in kilometers the plate will have traveled after $t = 10^5$ years.

A) 25 kmB) 2.5 kmC) 250 kmD) 0.25 km

Answer

✓ Correct Answer: Option B

Explanation: Solution: The distance d is given by $d = v \\times t$. $$d = 2.5 \ cm/year \\times 100,000 \years = 250,000 \cm$ Convert to kilometers:250,000 \cm = 2,500 \m = 2.5 \km$.

Question 2

2. A mountain stream flows from an elevation of $H_1 = 1450$ m down to a valley at $H_2 = 1250$ m. If the horizontal distance of the river's path is L = 50 km, what is the average river gradient G in meters per kilometer (m/km)?

A) 4 m/km 20 m/km

Question 3

3. Geologists observe that a river carves a canyon at a vertical erosion rate of r = 0.15 mm/year. How many years will it take for the river to carve a gorge that is H = 300 meters deep?

A) 200,000 yearsB) 45,000 yearsC) 2,000,000 yearsD) 20,000 years

Answer

✓ Correct Answer: Option C

Explanation: Solution: Convert depth to millimeters: 300 \m = 300,000 \ mm. Time $t = \\frac{H}{r}$: $$t = \\frac{300,000 \ mm}{0.15 \ mm/year} = 2,000,000 \years$$.

Question 4

4. The Richter scale is logarithmic. Every increase of 1 unit in magnitude corresponds to a 10-fold increase in measured amplitude. How much larger is the ground motion amplitude of a Magnitude 6 earthquake compared to a Magnitude 4 earthquake?

A) 20 timesB) 100 timesC) 1,000 timesD) 2 times

Answer

✓ Correct Answer: Option B

Explanation: Solution: The difference in magnitude is \\Delta M = 6 - 4 = 2. The amplitude increase is $10^{\\Delta M}$. $$10^2 = 100 \ times$$.

Question 5

5. The Mid-Atlantic Ridge spreads apart at a rate of 2 cm/year on each side of the ridge. Calculate the total width of the new ocean floor created between two points on opposite sides after $10^6$ years.

A) 20 kmB) 2 kmC) 40 kmD) 4 km

Answer

✓ Correct Answer: Option C

Explanation: Solution: Total spreading rate $v_{total} = 2 \ sides \\times 2 \ cm/year = 4 \ cm/year$. Total distance $d = v_{total} \\times t$: $$d = 4 \ cm/year \\times 1,000,000 \years = 4,000,000 \cm$ Convert to kilometers:4,000,000 \cm = 40,000 \m = 40 \km$.

Question 6

6. A normal fault in a rock layer shows a vertical displacement (throw) of 120 m and a horizontal displacement (heave) of 50 m. Using the Pythagorean theorem, calculate the total net slip (the actual diagonal distance the rock moved).

A) 130 mB) 170 mC) 150 mD) 110 m

Answer

✓ Correct Answer: Option A

Explanation: Solution: Total displacement $D = \\sqrt{x^2 + y^2}$. $$D = \\sqrt{120^2 + 50^2} = \\sqrt{14400 + 2500} = \\sqrt{16900} = 130 \m$$.

Question 7

7. Physical weathering breaks a solid granite cube with a side length of s = 10 cm into smaller cubes with side lengths of 1 cm each. By how much does the total surface area increase?

A) 600 sq cmB) 6000 sq cmC) 540 sq cmD) 5400 sq cm

Answer

✓ Correct Answer: Option D

Explanation: Solution: Original Surface Area $A_1 = 6s^2 = 6(10)^2 = 600 \cm^2$. Volume is $10^3 = 1000 \cm^3$. Each 1 cm cube has surface area $6(1)^2 = 6 \cm^2$. Total area of 1000 cubes $A_2 = 1000 \\times 6 = 6000 \cm^2$. Increase $= A_2 - A_1 = 6000 - 600 = 5400 \cm^2$.

Question 8

8. A glacier in the Himalayas is observed to flow at an average speed of 0.4 meters per day. Calculate the total distance the ice at the surface moves during a leap year (366 days).

A) 146 mB) 144 mC) 146.4 mD) 120.5 m

Answer

✓ Correct Answer: Option C

Explanation: Solution: Distance $d = \speed \\times \time$. $$d = 0.4 \ m/day \\times 366 \days = 146.4 \m$$.

Question 9

9. A river carries a sediment load of 2,000 kg of silt per day. Assuming the rate remains constant, how many metric tonnes of silt are transported by the river over a period of 3 years (assume 365 days per year)? [1 tonne = 1000 kg]

A) 730 tonnesB) 2190 tonnesC) 219 tonnesD) 6000 tonnes

Answer

✓ Correct Answer: Option B

Explanation: Solution: Total mass $M = 2000 \ kg/day \\times 365 \ days/year \\times 3 \years$. $M = 2,190,000 \kg Convert to tonnes:M = \\frac{2,190,000}{1000} = 2190 \ tonnes$.

Question 10

10. Due to isostatic rebound after the last ice age, a landmass is rising at a rate of 8 mm/year. What is the total vertical rise in meters over the last 12,000 years?

A) 96 mB) 9.6 mC) 960 mD) 0.96 m

Answer

✓ Correct Answer: Option A

Explanation: Solution: Total rise $H = 8 \ mm/year \\times 12,000 \years$. $H = 96,000 \ mm Convert to meters:96,000 \ mm = 96 \m$.

Accepted Answer

✓ Correct Answer: Option A

Explanation: Solution: Gradient $G = \\frac{\\Delta H}{L}$ where $\\Delta H = H_1 - H_2$. $\\Delta H = 1450 \m - 1250 \m = 200 \m $G = \\frac{200 \m}{50 \km} = 4 \ m/km$$.

Grade 9 : Social Science - 2. Shaping Earth (Set 2)

1. High-precision GPS stations on the Indo-Australian Plate show it is moving northward at a velocity of v = 2.5 cm/year. Calculate the total distance d in kilometers the plate will have traveled after $t = 10^5$ years.

2. A mountain stream flows from an elevation of $H_1 = 1450$ m down to a valley at $H_2 = 1250$ m. If the horizontal distance of the river's path is L = 50 km, what is the average river gradient G in meters per kilometer (m/km)?

3. Geologists observe that a river carves a canyon at a vertical erosion rate of r = 0.15 mm/year. How many years will it take for the river to carve a gorge that is H = 300 meters deep?

4. The Richter scale is logarithmic. Every increase of 1 unit in magnitude corresponds to a 10-fold increase in measured amplitude. How much larger is the ground motion amplitude of a Magnitude 6 earthquake compared to a Magnitude 4 earthquake?

5. The Mid-Atlantic Ridge spreads apart at a rate of 2 cm/year on each side of the ridge. Calculate the total width of the new ocean floor created between two points on opposite sides after $10^6$ years.

6. A normal fault in a rock layer shows a vertical displacement (throw) of 120 m and a horizontal displacement (heave) of 50 m. Using the Pythagorean theorem, calculate the total net slip (the actual diagonal distance the rock moved).

7. Physical weathering breaks a solid granite cube with a side length of s = 10 cm into smaller cubes with side lengths of 1 cm each. By how much does the total surface area increase?

8. A glacier in the Himalayas is observed to flow at an average speed of 0.4 meters per day. Calculate the total distance the ice at the surface moves during a leap year (366 days).

9. A river carries a sediment load of 2,000 kg of silt per day. Assuming the rate remains constant, how many metric tonnes of silt are transported by the river over a period of 3 years (assume 365 days per year)? [1 tonne = 1000 kg]

10. Due to isostatic rebound after the last ice age, a landmass is rising at a rate of 8 mm/year. What is the total vertical rise in meters over the last 12,000 years?