<< Chapter < Page Chapter >> Page >

Conceptual questions

Atmospheric pressure exerts a large force (equal to the weight of the atmosphere above your body—about 10 tons) on the top of your body when you are lying on the beach sunbathing. Why are you able to get up?

Got questions? Get instant answers now!

Why does atmospheric pressure decrease more rapidly than linearly with altitude?

Got questions? Get instant answers now!

What are two reasons why mercury rather than water is used in barometers?

Got questions? Get instant answers now!

[link] shows how sandbags placed around a leak outside a river levee can effectively stop the flow of water under the levee. Explain how the small amount of water inside the column formed by the sandbags is able to balance the much larger body of water behind the levee.

The figure shows a flooding river on the extreme right, with a levee set up on its left, and sandbags are stacked on the left of the levee. The height of the levee and that of the stacked sandbags is greater than the water level of the flooding river, so the water does not flow over their tops, but a leak under the levee allows some water to flow under it and reach the sandbags.
Because the river level is very high, it has started to leak under the levee. Sandbags are placed around the leak, and the water held by them rises until it is the same level as the river, at which point the water there stops rising.
Got questions? Get instant answers now!

Why is it difficult to swim under water in the Great Salt Lake?

Got questions? Get instant answers now!

Is there a net force on a dam due to atmospheric pressure? Explain your answer.

Got questions? Get instant answers now!

Does atmospheric pressure add to the gas pressure in a rigid tank? In a toy balloon? When, in general, does atmospheric pressure not affect the total pressure in a fluid?

Got questions? Get instant answers now!

You can break a strong wine bottle by pounding a cork into it with your fist, but the cork must press directly against the liquid filling the bottle—there can be no air between the cork and liquid. Explain why the bottle breaks, and why it will not if there is air between the cork and liquid.

Got questions? Get instant answers now!


What depth of mercury creates a pressure of 1.00 atm?

0.760 m

Got questions? Get instant answers now!

The greatest ocean depths on the Earth are found in the Marianas Trench near the Philippines. Calculate the pressure due to the ocean at the bottom of this trench, given its depth is 11.0 km and assuming the density of seawater is constant all the way down.

Got questions? Get instant answers now!

Verify that the SI unit of hρg size 12{hρg} {} is N/m 2 size 12{"N/m" rSup { size 8{2} } } {} .

h ρ g units = ( m ) kg/m 3 m/s 2 = kg m 2 / m 3 s 2 = kg m/s 2 1/m 2 = N/m 2
Got questions? Get instant answers now!

Water towers store water above the level of consumers for times of heavy use, eliminating the need for high-speed pumps. How high above a user must the water level be to create a gauge pressure of 3 . 00 × 10 5 N/m 2 size 12{3 "." "00" times "10" rSup { size 8{5} } `"N/m" rSup { size 8{2} } } {} ?

Got questions? Get instant answers now!

The aqueous humor in a person’s eye is exerting a force of 0.300 N on the 1 . 10 -cm 2 size 12{1 "." "10""-cm" rSup { size 8{2} } } {} area of the cornea. (a) What pressure is this in mm Hg? (b) Is this value within the normal range for pressures in the eye?

(a) 20.5 mm Hg

(b) The range of pressures in the eye is 12–24 mm Hg, so the result in part (a) is within that range

Got questions? Get instant answers now!

How much force is exerted on one side of an 8.50 cm by 11.0 cm sheet of paper by the atmosphere? How can the paper withstand such a force?

Got questions? Get instant answers now!

What pressure is exerted on the bottom of a 0.500-m-wide by 0.900-m-long gas tank that can hold 50.0 kg of gasoline by the weight of the gasoline in it when it is full?

1 . 09 × 10 3 N/m 2 size 12{1 "." "09" times "10" rSup { size 8{3} } `"N/m" rSup { size 8{2} } } {}

Got questions? Get instant answers now!

Calculate the average pressure exerted on the palm of a shot-putter’s hand by the shot if the area of contact is 50 . 0 cm 2 size 12{"50" "." 0`"cm" rSup { size 8{2} } } {} and he exerts a force of 800 N on it. Express the pressure in N/m 2 and compare it with the 1 . 00 × 10 6 Pa pressures sometimes encountered in the skeletal system.

Got questions? Get instant answers now!

The left side of the heart creates a pressure of 120 mm Hg by exerting a force directly on the blood over an effective area of 15 . 0 cm 2 . size 12{"15" "." 0`"cm" rSup { size 8{2} } } {} What force does it exert to accomplish this?

24.0 N

Got questions? Get instant answers now!

Show that the total force on a rectangular dam due to the water behind it increases with the square of the water depth. In particular, show that this force is given by F = ρ gh 2 L / 2 size 12{F=ρ ital "gh" rSup { size 8{2} } L/2} {} , where ρ size 12{ρ} {} is the density of water, h size 12{h} {} is its depth at the dam, and L size 12{L} {} is the length of the dam. You may assume the face of the dam is vertical. (Hint: Calculate the average pressure exerted and multiply this by the area in contact with the water. (See [link] .)

A two-dimensional view of a dam with dimensions L and h is shown. Force F at h is shown by a horizontal arrow. The force F exerted by water on the dam is F equals average pressure p bar into area A and pressure in turn is average height h bar into density rho into acceleration due to gravity g.
Got questions? Get instant answers now!

Questions & Answers

Prove that 1/d+1/v=1/f
James Reply
What interference
Moyinoluwa Reply
What is a polarized light called?
what is a half life
Mama Reply
the time taken for a radioactive element to decay by half of its original mass
what is radioactive element
Half of the total time required by a radioactive nuclear atom to totally disintegrate
radioactive elements are those with unstable nuclei(ie have protons more than neutrons, or neutrons more than protons
in other words, the radioactive atom or elements have unequal number of protons to neutrons.
state the laws of refraction
state laws of reflection
Why does a bicycle rider bends towards the corner when is turning?
When do we say that the stone thrown vertically up wards accelerate negatively?
Give two importance of insulator placed between plates of a capacitor.
Macho had a shoe with a big sole moving in mudy Road, shanitah had a shoe with a small sole. Give reasons for those two cases.
when was the name taken from
Biola Reply
retardation of a car
when was the name retardation taken
did you mean a motion with velocity decreases uniformly by the time? then, the vector acceleration is opposite direction with vector velocity
Atomic transmutation
Basirat Reply
An atom is the smallest indivisible particular of an element
mosco Reply
what is an atomic
Awene Reply
reference on periodic table
Titus Reply
what Is resonance?
Mozam Reply
phenomena of increasing amplitude from normal position of a substance due to some external source.
What is a black body
Amey Reply
Black body is the ideal body can absorb and emit all radiation
the emissivity of black body is 1. it is a perfect absorber and emitter of heat.
Why is null measurement accurate than standard voltmeter
Neemat Reply
that is photoelectric effect ?
Sabir Reply
It is the emission of electrons when light hits a material
is not just a material
it is the surface of a metal
what is the formula for time of flight ,maxjmum height and range
agangan Reply
what is an atom
an atom is the smallest particle of a element which can take part in chemical reaction.
how does a lightning rod protect a building from damage due to lightning ?
Faith Reply
due to its surface lustre but due to some factors it can corrode but not easily as it lightning surface
pls what is mirage
light rays bend to produce a displaced image of distant objects; it's an natural & optical phenomenon......
what is the dimensional formula for torque
Otto Reply
same units of energy
what is same units of energy?
M L2 T -2
it is like checking the dimension of force. which is ML2T-2
M L2 T-2
what is the significance of moment of inertia?
Practice Key Terms 1

Get the best College physics course in your pocket!

Source:  OpenStax, College physics. OpenStax CNX. Jul 27, 2015 Download for free at http://legacy.cnx.org/content/col11406/1.9
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'College physics' conversation and receive update notifications?