Fossil fuels . . . coal, oil, natural gas
Among primitive cultures, wood is an important source.
Answer:
Material's density
Explanation:
Seismic waves travel at different rates of speed based on a material's density. Hopefully, you understand that the Earth has three main layers: the crust, mantle, and core. Earthquake waves move faster through solids.
Answer:

Explanation:
Ok, the average speed can be calculate with the next equation:
(1)
Basically the car cover the same distance "d" two times, but at different speeds, so:

and the total time would be the time t1 required to go from A to B plus the time t2 required to go back from B to A:

From basic physics we know:

so:


Using the previous information in equation (1)

Factoring:
(2)
Finally, replacing the data in (2)

30x30=900
The answer is 900 meters after 30 seconds
Answer:
approximately 5.8 seconds
Explanation:
if you where to time how fast a rock would fall 12 meters it would approximately be 5.8 seconds