Which fundamental law forms the basis of Bernoulli's equation?

Is Bernoulli's equation unsteady? Explain.

Why do two rowing boats moving parallel to each other come closer (attract) to each other?

An ideal gas of density $\rho_1=0.2 \ kg \ m^{-3}$ enters a chimney of height $h$ at the rate of $\alpha=0.8 \ kg \ s^{-1}$ from its lower end,and escapes through the upper end as shown in the figure. The cross-sectional area of the lower end is $A_1=0.1 \ m^2$ and the upper end is $A_2=0.4 \ m^2$. The pressure and the temperature of the gas at the lower end are $600 \ Pa$ and $300 \ K$,respectively,while its temperature at the upper end is $150 \ K$. The chimney is heat insulated so that the gas undergoes adiabatic expansion. Take $g=10 \ ms^{-2}$ and the ratio of specific heats of the gas $\gamma=2$. Ignore atmospheric pressure. Which of the following statement$(s)$ is(are) correct?

$A$ horizontal pipe carries water in a streamlined flow. At a point along the pipe,where the cross-sectional area is $10 \text{ cm}^2$,the velocity of water is $1 \text{ ms}^{-1}$ and the pressure is $2000 \text{ Pa}$. What is the pressure of water at another point where the cross-sectional area is $5 \text{ cm}^2$ (in $Pa$)? [Density of water $= 1000 \text{ kgm}^{-3}$]

$A$ manometer connected to a closed tap reads $3.5 \times 10^5 \ N/m^2$. When the valve is opened,the reading of the manometer falls to $3.0 \times 10^5 \ N/m^2$. The velocity of the flow of water is ........ $m/s$.