Why are there 30 GPS satellites orbiting the Earth? To provide the power necessary to send out high-amplitude waves to GPS devices
If there were fewer, they'd be overloaded with information from all the GPS devices on Earth.
So that four satellites are above the horizon everywhere on Earth at all times.
15 provide coverage for all the GPS devices on Earth; the other 15 provide backup in case the main ones break down.

Scientist believe that earths core is around 6000°c where does this heat come from

In a 2010 article “fact check: eastern u.s. earthquake risk” by chris mould, the author provides as evidence the following statement by the united states geological survey: “although earthquakes may be less frequent in the eastern u.s., … urban areas in the east could face bigger losses because the shaking would affect much larger areas than similar quakes in the west. in addition, most homes and buildings in the east are not designed to withstand earthquakes.”this statement directly relates to which of the following concepts? a. vulnerabilityb. hazardc. riskd. severity

Does anyone know the answers for these