Q. If the water falls from a dam into a turbine wheel $19.6\ m$ below, then the velocity of water at the turbine is ($g = 9.8\ m/s^{2}$)
A) $9.8\ m/s$
B) $19.6\ m/s$
C) $39.2\ m/s$
D) $98.0\ m/s$
Explanation
(b) Potential energy of water = kinetic energy at turbine
$mgh = \frac{1}{2}mv^{2} \Rightarrow v = \sqrt{2gh} = \sqrt{2 \times 9.8 \times 19.6} = 19.6\ m/s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.