Question

Water falling from 50 m high fall is to be used for generating electric energy. If 1.8 x 10 kg of water falls per hour and half the gravitational potential energy can be converted into electric energy, how many 100 W lamps can be lit ?
Concept of Physics - 1 , HC VERMA , Chapter " Work and Energy"

Answer 1

Given in the question ,
Height H , = 50 m
Mass m = 1.8 × 10⁵ kg/hr = [1.8 × 10⁵ kg / 3600 s] = 50 kg/sec

Now the gravitational potential energy per sec.
= mgh
= 50 × 9.8 × 50
P.E = 24500 J.

So the electrical energy generated = 1/2 (P.E)
=1/2 (24500 J/sec)
= 12250 W.

So the number of 100 W lamp, will be lit.
= 12250 / 100
= 122.5

Or 122 bulb can be lit.



Hope it Helps

Answer 2

Answer:

when g=10 it comes .. = 125 bulbs