Surface Areas & Volumes | Exercise 13.5 | Q9

Question 9: A river 3 m deep and 40 m wide is flowing at the rate of 2 km per hour. How much water will fall into the sea in a minute?

Video Explanation

Explanatory Answer | Exrecise 13.5 Q9

Given Data

Depth of the river = 3 m
Width of the river = 40 m

Step 1: Compute the Rate of water flow in m/min

Rate of flow of river = 2 km/hr
1 km = 1000 m
1 hour = 60 minutes
Rate of flow = 2 × \\frac{1000}{60})
= \\frac{100}{3}) m/min

Step 2: Compute volume of water falling into sea per minute

Volume of water falling into sea per minute = Width × Depth × Rate of flow
Volume of water falling into the sea per minute = 3 × 40 × \\frac{100}{3}) m³/min
= 4000 m³/min

Exercise 13.1 | Surface Area of Cubes & Cuboids

1. Class 9 Exercise 13.1 Question 3 | Height of hall ▶
2. Class 9 Exercise 13.1 Question 6 | TSA of Herbarium ▶
3. Class 9 Exercise 13.1 Question 7 | Shanti Sweets ▶

Exercise 13.2 | Surface Area of Cylinders

1. Class 9 Exercise 13.2 Question 3 | CSA TSA of Metal Pipe ▶
2. Class 9 Exercise 13.2 Question 4 | Roller & Playground ▶
3. Class 9 Exercise 13.2 Question 9 | Cylindrical Petrol Tank ▶
4. Class 9 Exercise 13.2 Question 10 | CSA of Decorative Lampshade ▶

Exercise 13.3 | Surface Area of Cones

1. Class 9 Exercise 13.3 Question 5 | Length of Tarpaulin 3 m wide ▶
2. Class 9 Exercise 13.3 Question 8 | Cost of painting conical barricades ▶

Exercise 13.4 | Surface Area of Spheres & Hemispheres

1. Class 9 Exercise 13.4 Question 8 | Outer CSA of hemispherical bowl ▶
2. Class 9 Exercise 13.4 Question 9 | Surface area of sphere & Cylinder ▶