Answer:
The idea behind space expansion is that after the big bang, the universe started infinitely expanding. It's also called metric expansion. Stephen Hawking's A Brief History of Time goes further into detail on this.
Answer:
Explanation:
there could be earthquakes or the tectonic plates under can make it fall apart, natural disasters
hope this helps!!
Diffraction means spreading out of waves that has the same wavelength as the size of the gap. Sound waves have high wavelength and so it diffracts\spreads out and enables anyone to hear your voice from anywhere outside the room.
For inside the room, the sound waves doesn't actually diffract. They collide with the air particles, causing a series of compressions and rarefactions which spreads out in the air particles and anyone can hear your voice.
Air is the medium for the sound waves to travel.
Answer:
Bears lose necessary body fat because they must swim longer in open ocean water.
Explanation:
Polar bears, like their cousins, the grizzly bears, must build up a store of body fat that they can live off of during the winter months. This is especially true of mother bears who give birth to cubs during this time and need enough nourishment to feed the cubs.
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