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A hydraulic jump is a 2m wide rectangular channel which is horizontal and frictionless. The post-jump depth and velocity are 0.8 m and 1m/s, respectively. The pre-jump velocity is ___________ m/s. (use g = 10 m/s²)
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- 3.56 m/s
- 4.94 m/s
- 6.54 m/s
- 4 m/s
Correct Option: B
4.94
B = 2m, y2 = 0.8m, V2 = 1 m/s
| F2 = | ||
| √gy2 |
| = | = 0.35 | |
| √10 × 0.8 |
| = - | + | √1 + 8F²2 | |||
| y2 | 2 | 2 |
| ⇒ | = | + | √1 + 8 × (3.5)²2 | = 0.203 | |||
| 0.8 | 2 | 2 |
∴ y1 = 0.8 × 0.203 = 0.162 m
Q = AV2
= B.y2 × V2
= By1 × V1
⇒ 0.8 × 1 = 0.162 × V1
⇒ V1 = 4.94 m/s
