A water tank is in the form of a cube of side 2 m. It has an inlet in the shape of a circle with radius 3.5 cm. How long will it take to fill the tank (approximately), if the water is flowing at a speed of 2 m/s?

Explanation

The volume of the cubic tank is 2 × 2 × 2 = 8 cubic meters. The inlet has a circular cross-section with radius 3.5 cm, so the area of the inlet is 𝜋 × (0.035 ) 2 ≈ 0.00385 square meters. With water flowing at 2 m/s, the volume flow rate is 0.00385 × 2 = 0.0077 cubic meters per second. Therefore, the time to fill the tank is 8 /0.0077 ≈ 1039 seconds, or roughly 17.3 minutes.