6.7 Assess Your Understanding

Concepts and Vocabulary

Question

Pressure is defined as the _____exerted per unit area.

Question

True or False Hydrostatic pressure on a plate increases as the depth of the plate in a fluid increases.

Question

Multiple Choice In SI units, the [(a) newton, (b) pascal, (c) joule, (d) slug] is the unit measure of pressure.

Question

True or False The hydrostatic force \(F\) due to the pressure exerted by a fluid of mass density \(\rho\) on a plate of area \(A\) suspended horizontally in the fluid at a depth \(h\) is \(F=\rho ghA,\) where \(g\) is the acceleration due to gravity.

457

Skill Building

In Problems 5–8, the figure shows a vertical cross section of a container filled with water. Find the hydrostatic force of the water on the end of each container shown.

Question

Question

Question

Question

Question

A rectangular plate of width \(2\textrm{ m}\) and height \(6\textrm{ m}\) is suspended vertically in a pool of water so that the top of the plate is even with the surface of the water. What is the force due to water pressure on one side of the plate?

Question

If the plate in Problem 9 is suspended in the water so that the top of the plate is \(1\textrm{ m}\) below the water surface, what is the force due to water pressure on one side of the plate?

Applications and Extensions

Question

Hydrostatic Force in a Swimming Pool A swimming pool is in the shape of a rectangular parallelepiped \(6\textrm{ ft}\) deep, \(30\textrm{ ft}\) long, and \(20\textrm{ ft}\) wide. If the pool is full of water, what is the force due to water pressure on one short side of the pool? (Hint: The weight density of water is \(62.5\textrm{ lb/ft}^{2}\))

Question

Hydrostatic Force in a Swimming Pool For the pool in Problem 11, what is the force due to water pressure on one long side of the pool?

Question

Hydrostatic Force in a Trough A trough whose cross section is a trapezoid is \(1\textrm{ m}\) across at the bottom, \(5\textrm{ m}\) across at the top, and \(2\textrm{ m}\) deep. If the trough is filled to 1 m with water, what is the force due to water pressure on one end of the trough?

Question

Hydrostatic Force in a Trough A trough whose cross section is an equilateral triangle with side \(2\textrm{ m}\) long is filled with water. What is the force due to water pressure on one end of the trough?

Question

Hydrostatic Force in a Trough A trough whose cross section is a semicircle of radius \(2\textrm{ m}\) is filled with water. What is the force due to water pressure on one end of the trough?

Question

Hydrostatic Force on a Floodgate Find the hydrostatic force on the face of a vertical floodgate in the shape of an isosceles triangle whose base is \(1.5\textrm{ m}\) and whose height is \(1\textrm{ m}\), if its base is on the surface of the water. See the figure.

Question

Hydrostatic Force on a Dam A vertical masonry dam in the form of an isosceles trapezoid is \(200\textrm{ m}\) long at the surface of the water, \(150\textrm{ m}\) long at the bottom, and \(60\textrm{ m}\) high. What force must it withstand?

Question

Hydrostatic Force in an Oil Tank A tank filled with a half load of fuel oil is in the shape of a right circular cylinder lying on its side. If the radius of the cylinder is \(4\textrm{ ft}\) and the weight density of the fuel oil is \(60\textrm{ lb/ft}^{2}\), find the hydrostatic force due to the pressure of the oil on one end of the cylinder.

Question

Hydrostatic Force on a Submarine A vertical viewing plate in a submarine is a circle of radius \(1\textrm{ m}\). If the depth of the center of the viewing plate is \(5\textrm{ m}\) below the surface of the water, what is the hydrostatic force due to water pressure on one side of the plate? The mass density of sea water is \(1025\textrm{ kg/m}^{3}\).

Question

Hydrostatic Force on a Submarine A vertical viewing plate of a submarine has a perimeter given by the fat circle \(x^{4}+y^{4}=1.\) If the depth of the center of the viewing plate is \(5\) m below the surface of the water, find the hydrostatic force due to water pressure on the plate.

Question

Hydrostatic Force in a Gas Tank The gas tank in a sports car is a cylinder lying on its side. If the diameter of the tank is \(0.5\textrm{ m}\) and if the tank is filled with gasoline to within \(0.25\textrm{ m}\) of the top, find the force on one end of the tank. The density of gasoline is \(690\textrm{ kg/m}^{3}\).