Answer:
the power that can be generated by the river is 117.6 MW
Explanation:
Given that;
Volume flow rate of river v = 240 m³/s
Height above the lake surface a h = 50 m
Amount of power can be generated from this river water after the dam is filled = ?
Now the collected water in the dam contains potential energy which is used for the power generation,
hence, total mechanical energy is due to potential energy alone.
= m(gh)
first we determine the mass flow rate of the fluid m
m = p×v
where p is density ( 1000 kg/m³
so we substitute
m = 1000kg/m³ × 240 m³/s
m = 240000 kg/s
so we plug in our values into (
= m(gh) kJ/kg )
= 240000 × 9.8 × 50
= 117600000 W
= 117.6 MW
Therefore, the power that can be generated by the river is 117.6 MW
Kinetic energy per unit of mass is

Given, 
Therefore,


Now potential energy per unit mass is

Given, 
Therefore,


Thus, total mechanical energy of the river water per unit mass is


OR

Answer:
d' = d /2
Explanation:
Given that
Distance = d
Voltage =V
We know that energy in capacitor given as



If energy become double U' = 2 U then d'



2 d ' = d
d' = d /2
So the distance between plates will be half on initial distance.