According to the Big Bang theory how long ago did the universe started??
13 to 15 billion years ago
Answer:
for students to do nothing
Explanation:
because doing nothing is not a course goal
How do you get out of a room with only a mirror and a table?
Look in the mirror you see what you saw, use the saw to cut the table, half and half makes a hole, jump in it.
Thought you would like that.
<h2>
Answer: an underground lake</h2>
Explanation:
In general, sound (mechanical waves) travels faster in solids than in liquids, and faster in liquids than in gases. This is because <u>the speed of the mechanical waves is determined by a relationship between the elastic properties of the medium </u>in which they are propagated and the mass per unit volume of the medium (that is:<u>density</u>).
In other words: The speed of sound varies depending on the medium through which the sound waves travel.
So, if we are told the sound wave initially had a speed of 4,000 m/s and it suddenly decreases to 1,500 m/s, this means the sound waves passed from a solid medium to a liquid medium.
Hence, the correct option is: an underground lake.
