Answer:
7.89 m/s
Explanation:
Given that
Width of the river, b1 = 12 m
Width of the river, b2 = 5.8 m
Depth of the river, d1 = 2.7 m
Depth of the river, d2 = 0.85 m
Speed of the river, v1 = 1.2 m/s
Speed of the river, v2 = ?
Area of the river before the rapid, a1 = 12 * 2.7 = 32.4 m²
Area of the river after the rapid, a2 = 5.8 * 0.85 = 4.93 m²
To solve this question, we use a relation between the speed of the river and the volume of the river. We say,
Area1 * velocity1 = Area2 * velocity2, and when we substitute the values for each other we have
32.4 * 1.2 = 4.93 * v2
38.88 = 4.93v2
v2 = 38.88 / 4.93
v2 = 7.89 m/s
Therefore, the speed of the river after the rapid is 7.89 m/s
