(1) 求距离h；
(2) 水面下0.3m处的M点 的压强为多少？
(3) M点相对于基准面1-1的测压管水头是多少？ (h=4.54m，Pm=-41.6kPa，hm=-4.24m)
2.9 An upright U-tube is fixed on the hood of a car which traveling in a straight-line, with a constant acceleration a=0.5m/s2. The length L=500mm. Find the height difference of the two free surfaces in the U-tube.
一竖直的U形管安装在以匀加速度a=0.5m/s2作直线运行的车罩上，长度L=500mm。求U形管内两自由液面的高度差。 (25.5mm)
Problem 2.9 2.10 According to the diagram, an open tank containing water moves with an acceleration a=3.6m/s2, along a slope of 30o. What is the inclined angle ? with the horizontal plane and the equation of water pressure p at the free surface?
如图所示，一盛水的开口容器以加速度a=3.6m/s2沿30o的斜面运动。求自由液面与水平面的夹角?，并写出水的压强p的分布方程。
(?=15o，p=pa+?gh)
Problem 2.10
2.11 As shown in the figure, a gate of 2m wide, extends out of the plane of the diagram toward the reader. The gate is pivoted at hinge H, and weighs 500kg. Its center of gravity is 1.2m to the right and 0.9m above H. For what values of water depth x above H will the gate remain closed? (Neglect friction at the pivot point and neglect the thickness of the gate) 如图所示，闸门宽2m，重500kg，绕铰链H转动。闸门重心在距右端1.2m处且高于H 0.9m。问铰链H上方水深x为多少时，闸门
将关闭？（忽略铰链摩擦及闸门的厚度）(1.25m) Problem 2.11
2.12 A flat 1 m high gate is hinged at point O, and can rotate around the point (see attached diagram). The height of point O is a=0.4m. What is the water depth when the gate can automatically open around point O?
一1米高的平板闸门在O点处用铰链连接，且可绕铰链转动（见附图）。O点的高度为a=0.4m。水深多少时，闸门将自动开启？ (h=1.33m)
Problem 2.12
2.13 As shown in the diagram, a closed tank forming a cube is half full of water, find: (a) the absolute pressure on the bottom of the tank, (b) the force exerted by the fluids on a tank wall as a function of height, (c) the location of the center of pressure by water on the tank wall.
如图所示，一密闭立方体水箱装了一半的水，求：(a) 箱底的绝对压强；(b) 将流体对一侧箱壁的作用力表示为高度的函数；
(c) 水对箱壁的压力中心位置。 Problem 2.13 (17.8kPa，F=2h(8000+0.5?gh)，2/3)
2.14 A circular sluice gate of diameter d=1m is submerged in water as shown in the figure. The slant angle ?=60o, the submerged depth hc=4.0m, and the weight of the gate FG=1kN. Determine the magnitude of the vertical force T so as to make the gate rotate upward about axis a (neglect friction at axis a).
如图所示的一直径d=1m圆形闸门淹没于水中。倾角?=60o，淹深hc=4.0m，闸门重FG=1kN。求使闸门绕a轴向上转动的铅直力T的大小。(230kN)
Problem 2.14
2.15 The gate M shown in the figure rotates about an axis through N. If a=33m, b=13m, d=20m and the width perpendicular to the plane of the figure is 3m, what torque applied to the shaft through N is required to hold the gate closed?
图示闸门M绕N轴转动。如a=33m、 b=13m、d=20m且与图形垂直的宽度为3m，要使闸门关闭，需要施加多大的力矩在转轴上？(666?103kN?m)
Problem 2.15
2.16 Find the horizontal and vertical components of the force exerted by fluids on the fixed circular cylinder shown in the figure, if:(1) the fluid to the left of the cylinder is a gas confined in a closed tank at a pressure of 35kPa, and (2) the fluid to the left of the cylinder is water with a free surface at an elevation coincident with the uppermost part of the cylinder. Assuming in both cases that normal atmospheric pressure conditions exist to the right and top of the cylinder.
求下述流体对图示圆柱体所施加的水平与铅直方向的分力。(1)圆柱体左边是压强为35kPa的密闭气体；(2)圆柱体左边是自由液面刚好与柱顶平齐的水。设两种情况下圆柱
体的右边与顶部为标准大气压。 Problem 2.16 ((1) Fx=130.5kN，Fz=35kN；(2) Fx=68.1kN，Fz=100.5kN)
2.17 The cross section of a tank is as shown in the figure. BC is a cylindrical surface with r=6m, and h=10m. If the tank contains gas at a pressure of 8kPa, determine the magnitude and location of the horizontal and vertical force components acting on unit width of tank wall ABC. 图示为一容器的剖面，BC是半径r=6m的圆柱面。容器高h=10m。如果容器装有压强为8kPa的气体，求作用在容器壁ABC上单位宽度的水平分力与铅直分力的大小与作用位置。
(Fx=80kN，Fz=48kN) Problem 2.17
2.18 Find the minimum value of z for which the gate in the figure will rotate counterclockwise if the gate is: (a) rectangular 5m high by 4m wide; (b) triangular, 4m base as axis, height 5m. neglect friction in bearings.
Problem 2.18
当下述情况时，求使图示闸门沿逆时针方向转动的z的最小值：(a) 闸门为高5m、宽4m的矩形；(b) 闸门为上底4m（转轴）、高5m的三角形。 ((a) z=307.5m，(b)305m)
2.19 A curved surface is formed as a quarter of a circular cylinder with R=0.75m, as shown in the figure. The cylinder surface is w=3.55m wide (out of the plane of the figure toward the reader). Water standstill to the right of the curved surface to a depth of H=0.65m. Determine
(1) The magnitude of the hydrostatic force on the surface.
(2) The direction of the hydrostatic force. Problem 2.19 一曲面由半径为R=0.75m的四分之一的圆柱体组成，如图所示。圆柱面宽w=3.55m（垂直于图形平面）。曲面右侧静水深度H=0.65m。试求：
(1) 作用于曲面上静水压力的大小； (2) 静水压力的方向。 (Fx=7357N，Fz=6013N)
2.20 As shown in the diagram, there is a cylinder with diameter D=4m and length L=12m in water. The depth of water on the right and left side of the cylinder are 4m and 2m respectively. Find the magnitude and direction of the force on the cylinder exerted by water.
如图所示，直径D=4m、长L=12m Problem 2.20
的圆柱体放于水中，圆柱体左右两边水的深度分别为4m 和 2m。求水对圆柱体的作用力的大小与方向。
(Fx=706kN，Fz=1579kN)
2.21 As shown in the figure, determine the pivot location y of the rectangular gate, so that the gate will just open.
如图所示，求闸门刚好开启时转轴的位置y为多少。(y=0.44m)
Problem 2.21