All around the world the Coal is burning for various uses such as producing electricity etc and every year tons of Coal is burned all around the world and when these tons of Burned Coal ashes and gases Unite with the oxygen it added another ton of carbon dioxide in the Environment.
This tends to make a more effective blanket on the earth which tend to increase the earth's temperature and further ecological issues.
And, these effects remain for centuries which definitely going to affect our coming future generation.
Answer: Kinetic energy is entirely dependent on mass. Since Roberto has twice the mass of Mary, his kinetic energy will be twice as much. Hope this helps! :)