Science Unit 1 Fist actual test

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P-waves speed up at the mantle-core boundary, so we know the outer core is less rigid than the mantle.

False

Modern seismometers record ground motions using electronic motion detectors. The data are then kept digitally on a computer.

True

Waves of energy radiate out from an earthquake's focus.

True

Oceanic crust is less dense than continental crust.

False

If the earthquake has a deep focus, the surface waves are the largest ones recorded.

False

Scientists cannot use seismic waves to understand what makes up the Earth's interior.

False

Scientists know for fact exactly how the earth and the solar system formed.

False

Scientists know that the mantle is made of rock because they have taken samples by drilling into it since the 1960's.

False

Scientists know that the outer core is liquid and the inner core is solid because S-waves go through the outer core.

False

The asthenosphere rides on the lithosphere.

False

The oceanic crust is thicker than the continental crust.

False

Although we sometimes refer to Earth's plates as being plates of crust, the plates are actually made of lithosphere.

True

An iron meteorite is the closest thing to a sample of the core that scientists can hold in their hands.

True

Ancient impact craters found on the Moon and inner planets indicate that asteroid impacts were common in the early solar system.

True

As the core heats the bottom layer of mantle material, particles move more rapidly, decreasing its density and causing it to rise.

True

Because continental crust is thick and has relatively low density, continental crust rises higher on the mantle than oceanic crust, which sinks into the mantle to form basins.

True

Convection currents within Earth's mantle form as material near the core heats up.

True

Early in the planet's history there were many radioactive elements.

True

Earth formed at the same time as the other planets.

True

S-waves are larger than P-waves.

True

Surface waves arrive last.

True

Surface waves travel along the ground, outward from an earthquake's epicenter and cause the most damage of any seismic wave.

True

The asthenosphere is partially molten upper mantle material and behaves plastically and can flow.

True

The asthenosphere is solid upper mantle material that is so hot that it behaves plastically and can flow.

True

The crust is very thin relative to the radius of the planet.

True

The definition of the lithosphere is based on how Earth materials behave.

True

The energy from earthquakes travels in waves.

True

Earth came together from the cloud of dust and gas nearly 4.6 billion years ago.

True

Earth's outer core is liquid.

True

Just as a medical doctor uses an MRI, CT scan, or x-ray to see inside a patient's body, seismologists use wave energy to learn about Earth's interior.

True

Oceanic crust is composed of mafic magma that erupts on the seafloor to create basalt lava flows or cools deeper down to create the intrusive igneous rock gabbro.

True

The different densities of earth's layers cause seismic waves to be reflected or refracted (bent.)

True

Wave height is used to determine the magnitude of the earthquake

true

A seismograph is a paper record of the seismic waves the seismograph received

False

As the mantle material rises closer to the crust it heats up even more.

False

Continental crust is mafic and oceanic crust is felsic

False

Earth has a brittle asthenosphere riding on the plastic lithosphere.

False

Earth was struck so much in its first 500 million years causing it to cool greatly.

False

P-waves and S-waves move in a compression/expansion type motion, squeezing and unsqueezing Earth materials as they travel.

False

Radioactive decay absorbs heat.

False

S-waves are the fastest.

False

S-waves travel through solids, liquids, and gases while P-waves only move through solids.

False

Seismic waves are measured on a seismogram.

False

Seismic waves go the same speed through different materials.

False

Seismic waves travel outward in one direction from where the ground breaks (focus).

False

Seismograms can only tell you how strong an earthquake is

False

Since Earth has a magnetic field, there must be a gas within the planet.

False

The Earth's strong magnetic field is caused by conduction in the liquid outer core.

False

The deepest drill hole into the earth reached its core.

False

The heat that keeps the outer core from solidifying is produced by the breakdown of radioactive elements in the crust.

False

The height of a wave from the center line to its crest is its wavelength while the distance between waves from crest to crest (or trough to trough) is its amplitude.

False

The mantle is hot mostly because of the heat conducted from the crust.

False

The mantle is mostly iron metal.

False

When Earth first came together it was really cold.

False

When Earth was entirely molten, gravity drew lighter elements to the center and denser elements rose to the surface.

False

Earth's overall density is higher than the density of crustal rocks, so the core must be made of something dense, like metal.

True

Every wave has a high point called a crest and a low point called a trough.

True

Geologists study earthquake waves to "see" Earth's interior.

True

Gravity caused small bodies of rock and metal orbiting the Sun to smash together to create larger bodies.

True

Gravity caused the temperature and pressure of the early earth to increase by squeezing the material in its interior really hard.

True

If a material is able to move, even if it moves very slowly, convection currents can form.

True

If we could cut Earth open, we'd see the inner core at the center, then the outer core, the mantle in the middle and the crust on the outside

True

P-waves (primary waves) are fastest, traveling at about 6 to 7 kilometers (about 4 miles) per second, so they arrive first at the seismometer.

True

P-waves and S-waves are known as body waves because they move through the solid body of the Earth.

True

S-waves disappear at the mantle core boundary, so we know the outer core is liquid.

True

Scientists know that the core is metal based on the overall density of the planet, metallic meteorites, and earth's magnetic field.

True

Some seismic waves do not travel through liquids or gases.

True

The lithosphere is composed of both the crust and the portion of the upper mantle and behaves as a brittle, rigid solid.

True

The lithosphere is composed of both the crust and the portion of the upper mantle that behaves as a brittle, rigid solid.

True

The mantle is made of iron and magnesium rich silicate minerals.

True

The mantle is made of solid rock and is very hot.

True

The outer core is molten metal.

True

The separation of Earth into layers based on density is known as differentiation.

True

The study of seismic waves is known as seismology.

True

The two types of crust are oceanic crust and continental crust.

True

S-waves cannot travel through liquid.

true

The liquid outer core creates an S-wave shadow zone on the opposite side of the Earth from the quake.

true


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