Answer: I belive that the Answer is C.) Conduction
Explanation:
Fossil fuels . . . coal, oil, natural gas
Among primitive cultures, wood is an important source.
Answer:

Explanation:
The constant speed means that ball is not experimenting acceleration. This elements is modelled by using the following equation of equilibrium:


Now, the exerted force is:

The volume of a sphere is:



Lastly, the force is calculated:


Answer:3,45 x 10^9 N
Explanation: We have considered the total charge for each coin , this is the total atoms x 29 electrons for cooper and multiplier by electron charge, the total charge for each coin is 0,464 C
Finally we use the Coulomb law,
F=k Q/ (r)^2