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. \(p+\dfrac12\rho v^2+\rho gh\text{=constant}\)
2. \(p+\dfrac12\rho v^2\text{=constant}\)
3. \(\dfrac12\rho v^2+\rho gh\text{=constant}\)
4. \(p+\rho gh\text{=constant}\)

A wind with a speed of \(40~\text{m/s}\) blows parallel to the roof of a house. The area of the roof is \(250~\text{m}^2.\) 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:
\((\rho_{\text {air }}=1.2~\text{kg/m}^3)\)${\mathrm{ }}_{}$
1. \(4 \times 10^5~\text N,\) downwards
2. \(4 \times 10^5~\text N,\) upwards
3. \(2.4 \times 10^5~\text N,\) upwards
4. \(2.4 \times 10^5~\text N,\) 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.