Question

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 ?

Answer 1

Depth of river, h = 3m 

breadth, b = 40 m 

1 Km. = 1000 m 

∴ 2 Km. = 2000 m. 

Speed of the river per hour is 2 Km. 

For 60 minutes, 2000m 

For 1 minute …?…

\(= \frac{2000}{60}\)

= \(\frac{100}{3}\)m/minute

∴ Depth of river in 1 minute, l = \(\frac{100}{3}\)m. 

Volume of water flows in 1 minute, 

v = l × b × h 

= \(\frac{100}{3}\) × 40 × 3 = 4000 m³ 

∴ In One minute, 4000 m³ water reaches the sea.