Question

A water trough is 7 m long and has a cross-section in the shape of an isosceles trapezoid that is 30 cm wide at the bottom, 70 cm wide at the top, and has height 40 cm. If the trough is being filled with water at the rate of 0.2 m3/min how fast is the water level rising when the water is 20 cm deep

Answer 1

Explanation:

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Answer 2

The degree of fastness by which the water is rising is 210 seconds

Explanation:

The volume of the trough when the water depth is 20 cm is first calculated

Volume of the trough (Trapezoidal Prism) = LH (A + B) × 0.5

Where L is the length of the trough, H is the height of the trough and A and B are parallel width of the top and bottom of the trough

Volume of the trough = 7 × 0.2 (0.3 + 0.7) × 0.5 = 0.7m³

The fastness at which the water is rising is = Volume ÷ water flow rate = 0.7 ÷ 0.2 = 3.5 min = 210 seconds