91Ó°ÊÓ

Energy: The ability to perform work in physics. It can take many different forms, including potential, kinetic, thermal, electrical, chemical, nuclear, and others.

(a)

The fusion of all the hydrogen in Earth’s Ocean will produce ${10}^{34}\text{J}$of energy.

One millionth of this energy,

$$\begin{gathered} E_H=\frac{{10}^{34}\text{J}}{{10}^6} \\ ={10}^{28}\text{J} \end{gathered}$$

Annual world’s consumption of energy is,

$E_W=4×{10}^{20}\text{J}$

Number of years of world’s energy supplied by one millionth of oceans’ hydrogen fusion energy is,

$n=\frac{E_H}{E_W}$

Putting all known values,

$$\begin{gathered} n=\frac{{10}^{28}\text{J}}{4×{10}^{20}\text{J}} \\ =25×{10}^6 \end{gathered}$$

Therefore, One millionth of the oceans’ hydrogen fusion energy is enough to supply 25 million years of world’s energy.

(b)

The time 25 million years is a very long time, this time is much longer than a human can think of.

Thus, if we are able to use even one millionth of ocean’s hydrogen fusion energy, we will be able to supply enough energy for millions of years.