Answer:
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A secondary wave is a type of seismic wave that shakes particles at right angles to their direction of travel.
A seismic wave is a wave that travels through the Earth. It happens because of an earthquake, volcanic eruption, magma movement, a large landslide, and a large man-made explosion that produces low-frequency acoustic energy.
These waves are studied by seismologists and they record the waves using seismometers. In water, they use hydrophones or accelerometers. Seismic waves are different from seismic noise, which is persistent low-amplitude vibration arising from a variety of natural and anthropogenic sources.
The velocity of a seismic wave depends on the type of wave as well as the density and elasticity of the medium. Velocity tends to increase with depth through Earth's crust and mantle but drops sharply going from the mantle to Earth's outer core.
Earthquakes create distinct types of waves with different velocities.
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The measure of the average energy of motion of particles in matter. Thermal Energy. The total energy of motion of particles of matter
Apparent magnitude does not consider distance.
A light-year is the speed at which light travels from the sun to Earth.
Planets sometimes look brighter than stars because of reflected light from the sun.