Describe the energy flow in a hydroelectric power plant and calculate its efficiency given specific parameters.

Given volume $V = 150 \text{ cm}^3/\text{s}$.
Convert $\text{cm}^3$ to $\text{m}^3$:

$$150 \text{ cm}^3 = 150 \times (10^{-2} \text{ m})^3 = 150 \times 10^{-6} \text{ m}^3 = 1.5 \times 10^{-4} \text{ m}^3$$

Density of water $\rho = 1000 \text{ kg/m}^3$.
Mass of water discharged per second $\frac{m}{t} = \rho \times \frac{V}{t}$:

$$\frac{m}{t} = 1000 \text{ kg/m}^3 \times 1.5 \times 10^{-4} \text{ m}^3/\text{s} = 0.15 \text{ kg/s}$$

Given height $h = 38 \text{ m}$ and acceleration due to gravity $g = 9.81 \text{ m/s}^2$.

$$P_{input} = \frac{mgh}{t} = \left(\frac{m}{t}\right)gh$$ $$P_{input} = 0.15 \text{ kg/s} \times 9.81 \text{ m/s}^2 \times 38 \text{ m} = 55.803 \text{ W}$$

Given efficiency $\eta = 72\% = 0.72$.

$$P_{output} = P_{input} \times \eta$$ $$P_{output} = 55.803 \text{ W} \times 0.72 = 40.17816 \text{ W}$$

Rounding to three significant figures:
The power output from the turbine is $\boxed{\text{40.2 W}}$.

1. (a) (iii)
Fossil fuels are non-renewable energy sources formed over millions of years from the decomposition of ancient organic matter (e.g., coal, oil, natural gas). Bio-fuels are renewable energy sources derived from recently living organisms or their metabolic byproducts (e.g., ethanol from corn, biodiesel from vegetable oils).

1. (b) (i)
One advantage nuclear fusion has over nuclear fission is that it produces less radioactive waste with shorter half-lives, and the fuel sources (isotopes of hydrogen) are abundant.

1. (b) (ii)
The fusion reaction is: $^2_1\text{H} + ^3_1\text{H} \rightarrow ^4_2\text{He} + ^1_0\text{n} + \Delta E$
Given masses:
Mass of $^2_1\text{H} = 2.015 \text{ u}$
Mass of $^3_1\text{H} = 3.017 \text{ u}$
Mass of $^4_2\text{He} = 4.004 \text{ u}$
Mass of $^1_0\text{n} = 1.009 \text{ u}$

$$\Delta E = \Delta m \times 931.5 \text{ MeV/u}$$ $$\Delta E = 0.019 \text{ u} \times 931.5 \text{ MeV/u} = 17.7005 \text{ MeV}$$

Rounding to three significant figures:
The energy released is $\boxed{\text{17.7 MeV}}$.