9th Grade Science
4th Nine Weeks Exam
Review
1.The two layers that make up the lithosphere are the
2.The three main layers of Earth’s interior are the
3.New ocean crust is formed along
4.A subducting oceanic plate
5.Plates slide pass each other, and crust is neither created nor destroyed at a
6.What is a break in a rock mass along which movement occurs?
7.Stress in Earth’s crust is caused by
8.What is the name of the location within Earth where an earthquake begins?
9.P waves
10.Geologists have inferred that Earth’s outer core is liquid because
11.List three situations where no work is done.
12.What is the unit of work?
13.If you exert a force of 10.0 N to lift a box a distance of 0.75 m, how much work do you do?
14.If you perform 30 joules of work lifting a 20-N box from the floor to a shelf, how high is the shelf?
15.The SI unit of power is the
16.The power of a machine measures
17.If you exert a force of 500 N to walk 4 m up a flight of stairs in 4 s, how much power do you use?
18.Explain how to increase power through work and time.
19.A machine is a device that can multiply
20.How can a machine make work easier for you?
21.The actual mechanical advantage of a machine
22.If you have to apply 30 N of force on a crowbar to lift an rock that weights 330 N, what is the actual
mechanical advantage of the crowbar?
23.A 100-m long ski lift carries skiers from a station at the foot of a slope to a second station 40 m
above. What is the IMA of the lift?
24.Reducing friction in a machine
25.The efficiency of a machine is always less than 100 percent because
26.A mechanical device requires 400 J of work to do 340 J of work in lifting a crate. What is the
efficiency of the device?
27.An inclined plane reduces the effort force by
28.An ax is an example of a(an)
29.The ideal mechanical advantage of a pulley system is equal to the
30.The ideal mechanical advantage of a wheel and axle is found by
31.An example of a compound machine is a
32.A machine is classified as a compound machine if it
33.A mechanical wave moves through a medium, which can be
34.Transverse and longitudinal waves both
35.Which type of mechanical wave needs a source of energy to produce it?
36.Which wave causes the medium to vibrate only in a direction parallel to the wave’s motion?
37.A disturbance sends ripples across water in a tub. These ripples are an example of a
38.In an earthquake, a P wave is a longitudinal wave. It moves through soil and rock as a
Figure 17-1
39. Figure 17-1 shows a wave movement during 1 second. What is the frequency of this wave?
40. To determine the speed of a wave, you would use which of the following formulas?
41. A wave has a wavelength of 15 mm and a frequency of 4.0 hertz. What is its speed?
42.To find amplitude, measure
43.When a wave strikes a solid barrier, it behaves like a basketball hitting a backboard. This wave
behavior is called
44.How does reflection differ from refraction and diffraction?
45.What is one property of a wave that determines how much it will diffract when it encounters an
obstacle?
46.Suppose two waves collide and the temporary combined wave that results is smaller than the
original waves. What term best describes this interaction?
47. A sound wave is an example of a
48. In which medium does sound travel the fastest?
Magnetic mysteries of Earth's Core
By Gaby Hornsby BBC Horizon
Earthquakes, explosions and observations of Earth's ever-changing magnetic field are helping
scientists open up a new window on the heart of our planet.
When Jules Verne wrote A Journey to the Centre of the Earth over 100 years ago, he imagined a
place of glowing crystals and a turbulent sea, complete with prehistoric animals and giant
mushrooms.
What was actually beneath our feet was a complete enigma. Even to this day scientists
astonishingly know more about the rings of Saturn than they do about the core of our own planet.
But that is beginning to change. "We're at a golden age in terms of the real discovery of the bulk
of the deep Earth," says seismologist Professor Rick Aster.
And remarkably, not everything Verne imagined was wrong.
Wanting to discover the truth about the centre of our world is as basic a human urge as
wondering what is on the Moon, although the latter has proved far easier to explore.
But scientists are also fascinated by the Earth's core because it is responsible for creating our
planet's magnetic field which is vital to life.
As a tool for navigation, it helps honey bees find their hive, while sea turtles, birds and
butterflies use it to migrate over long distances.
The magnetic field also acts as a protective barrier between us and some of the dangers of space,
shielding us from radiation in the solar wind.
Physically traveling to the core has proved a non-starter though, because of the rapidly
increasing pressures and temperatures.
Even with remote drilling, the deepest we have managed to penetrate is 12km at the Kola
Superdeep Borehole in Russia - a measly 0.2% of the way to the centre of the Earth.
Molten metal
But seismology has allowed scientists to sense right into the core of the planet. The seismic
waves generated during major earthquakes travel from one side of the Earth to the other,
allowing scientists to build up a picture of the interior.
Seismology is "the killer application", says Aster, showing us the Earth has a molten outer-core,
"an enormous ocean of white hot molten metal that's almost as runny as water".
This core is as large as Mars. But - like a planetary Russian doll - another core was found within
this one. An inner-core - a solid metal ball almost the size of the Moon.
Scientists believe the solid inner core is made of an iron-nickel alloy.
To understand what form it might take under the extreme conditions at the centre of the Earth,
Professor Kei Hirose set himself a seemingly impossible challenge: recreate the conditions of the
core in his lab at the SPring-8 synchrotron near Osaka, Japan. After 10 years of trying, he has
finally succeeded.
Crystal forest
Extreme conditions found at the Earth's core have been recreated in the laboratory
He has created an incredibly powerful vice using the tips of two diamonds. Between them he has
pressurized a sample of iron-nickel to three million times atmospheric pressure and heated the
sample to about 4,500C.
Under these extraordinary conditions, the crystal structure of iron-nickel alloy changed and the
crystals rapidly grew in size. "We may have very big crystals at the centre of the Earth, maybe
up to 10km," says Hirose.
These crystals would all align "like a forest", says Hirose, pointing at the poles.
The bulk of the Earth's magnetic field is generated not in the inner-core but in the molten metal
of the outer-core. This acts as a massive electromagnetic dynamo powered by the Earth's rotation
and the long-term cooling of the planet.
But although the basic principle is understood, the details of how the molten metal moves are a
mystery. As Earth rotates and loses heat from the centre, complex patterns of flow are created
within this vast ocean.
"You might think of the core like the atmosphere of the Earth, being a very restless place with
storms and fronts and bad weather," says geophysicist Professor Dan Lathrop from the
University of Maryland. He has built himself a massive model of the core to help explain
something strange about the field - it is never fixed but constantly fluctuating.
The Earth's magnetic field has been steadily weakening over the past 180 years. And there is one
patch that is weakening faster than any other. It is an area scientists have dubbed the "South
Atlantic Anomaly", which sits over the South Atlantic and the centre of South America.
It is a known hazard for spacecraft because it creates a dip in the field, allowing charged particles
into the orbit of satellites and upsetting their electronics and instrumentation.
Magnetic flip
Scientists have mapped the growth of a weak zone in the Earth's magnetic field
But what some scientists suspect is that it could be much more than an inconvenience to satellite
operators - it could be the first indication of a profound change in Earth's magnetic field.
When scientists mapped the Earth's magnetic field down to the level of the outer-core, they
discovered that under the South Atlantic Anomaly the simple north-south divide we know at the
surface had broken down. There are patches where the field has actually flipped and points north
instead of south.
Using his weather analogy, Lathrop believes "a particularly violent or unusual patch of weather"
in the molten metal of the outer-core is responsible for reversing the field.
If these patches continue to deepen and spread, the entire Earth's magnetic field could reach a
tipping point and flip, he believes.
It is not something that would happen overnight - it could take thousands of years, during which
period the field would be pretty confused.
The magnetic poles could wander to the equator for example, and take with them the spectacular
Northern Lights. It would not be out of character - the shifting flows of the core have reversed
Earth's field hundreds of times before.
"It's not a question of if the Earth is going to reverse the magnetic field, but when," says Lathrop.
Exactly when this might be remains one of the core's many mysteries. But after centuries of
speculation, scientists are finally beginning to understand this great wonder lying 6,000km
beneath our feet.
END OF ARTICLE ----------------------------------------------------------------49.The author’s main purpose for writing this article is to
50.One main idea of the last section, Earth’s Core and Its Magnetic Field, is that
51.The purpose of the last sentence in this article is to
52.A geophysicist is a person who
53.Why does the author refer to the earth’s crust as its “skin?”
54.From this article, the invention of the seismograph has been important for all of the following
reasons except
55.The author of this article believes that
56.By analyzing more than 30 years of seismographic data, scientists have learned that
Figure 22-1
57. In Figure 22-1, the P wave will reach a seismograph located 40 kilometers from the earthquake
epicenter in ____________________ seconds.
58. A(An) ____________________ is a device that is used to detect and record seismic waves.
59. Due to sea-floor spreading, the youngest rocks in the ocean floor are found near a(an)
_________________________.
60. Waves in a rope are transverse waves because the medium’s vibration is
_________________________ to the direction in which the wave travels.
61. the thin and solid outermost layer of the Earth above the mantle
62. the layer of hot, solid material between Earth's crust and core
63. the solid, outer layer of the earth that consists of the crust and the rigid upper part of the mantle
64. The solid, plastic layer of the mantle beneath the lithosphere; made of mantle rock that flows
very slowly, which allows tectonic plates to move on top of it
65. a layer of molten iron and nickel that surrounds the inner core of Earth
66. 5-70 km thick
67. 2890 km thick
68. 100 km thick
69. 2260 km thick
70. granitic part of the Earth's crust that makes up the continents, lower density
71. basaltic portion of Earth's crust that is usually below the oceans, thinner and higher in density
72. more dense oceanic plate dives under continental plate. forms a trench. causes volcanoes, and
earthquakes
73. Andes Mountains
74. one oceanic plate dives underneath another oceanic plate, forms trenches, subduction
zones,forms volcanic island arcs, causes earthquakes, slab pull
75. Aleutian Islands, Japan Island Arc
76. 2 plates with same density collide, fold and crumple. form mountains from pushing up against
each other
77. Himalayas, Appalachians
78.a boundary in which two plates slide past each other without creating or destroying lithosphere
79. San Andreas Fault
80. The region where oceanic plates sink down into the asthenosphere.trench depression formed at
a subduction zone
81. An arc of volcanoes caused by subduction of an oceanic plate under a continental plate
82. Linear group of volcanoes that form due to subduction of an oceanic plate under another oceanic
plate.
83. Andes Mountains
84. Japan
85.Study of Earth's magnetic record using data gathered from iron-bearing minerals in rocks that have
recorded the orientation of Earth's magnetic field at the time of their formation
86. a concentration of heat in the mantle capable of producing magma, which rises to Earth's surface
87. The Pacific Plate moves over a hot spot, producing the Hawaiian Islands
88. there is a close link between the location of deep focus earthquakes and ocean trenches
89. a continuous elevated zone on the floor of all the major ocean basins and varying in width from
1000-4000km;
90. the rifts at the crests represent divergent plate boundaries (Mid-Atlantic Ridge)
91. New seafloor is formed when magma is forced upward toward the surface at a mid-ocean ridge
Figure 22-1
92. Use Figure 22-1 to determine when the P waves and S waves reached a seismograph station
located 40 km from the earthquake epicenter.
93. A worker uses a cart to move a load of bricks weighing 680 N a distance of 10 m across a
parking lot. If he pushes the cart with a constant force of 220 N, what amount of work does he
do?
Figure 22-3
94. Interpreting Graphics In Figure 22-3, what process is occurring in the area labeled D, and what
feature will result at C?
95. Interpreting Graphics In Figure 22-3, what is occurring at A?
96. Interpreting Graphics In Figure 22-3, what is occurring at the feature labeled B?
97. Using Models Use Figure 22-3 to identify where new crust is being created and where it is being
destroyed. Give the letter on the diagram and the terms used to describe these areas.
98. Classifying In Figure 22-3, what type of plate boundary is illustrated at E?
Figure 14-2
99. Calculating What is the IMA of the ramp in Figure 14-2? Show your work.
100. Applying Concepts If the ramp shown in Figure 14-2 was coated with a smoother surface, how
would the AMA of the ramp change?