A fluid of density \(\rho~\)is flowing in a pipe of varying cross-sectional area as shown in the figure. Bernoulli's equation for the motion becomes:
              
1.  \(p+\frac12\rho v^2+\rho gh\text{=constant}\)
2. \(p+\frac12\rho v^2\text{=constant}\)
3. \(\frac12\rho v^2+\rho gh\text{=constant}\)
4. \(p+\rho gh\text{=constant}\)

A wind with a speed of \(40\) m/s blows parallel to the roof of a house. The area of the roof is \(250\) m². Assuming that the pressure inside the house is atmospheric pressure, the force exerted by the wind on the roof and the direction of the force will be: (\(\rho_{\text {air }}=1.2\)${\mathrm{ }}_{}\mathrm{kg}/{\mathrm{m}}^3$)
1. \(4 \times 10^5\) N, downwards
2. \(4 \times 10^5\) N, upwards
3. \(2.4 \times 10^5\) N, upwards
4. \(2.4 \times 10^5\) N, downwards

Water is flowing through a long horizontal tube. Let \(P_A\) and \(P_B\) be the pressures at two points \(A\) and \(B\) of the tube.