Question

If the water falls from a dam into a turbine wheel 19.6 m below, then the velocity of water at the turbines, is ( take $g=9.8m/s^2$ )

• A. 9.8 m/s
• B. 19.6 m/s
• C. 39.2 m/s
• D. 98.0 m/s

Answer 1

The correct option is B 19.6 m/s

$\Delta KE=-\Delta U$

$0.5m{v}^2-0.5m{u}^2=mgh$ since u = 0.

$v=\sqrt{2gh}=\sqrt{2\times 9.8\times 19.6}=19.6m/s$