Possibilities . . .
-- nuclear reaction
-- nuclear fission
-- nuclear fusion
-- radioactive decay.
Any of these makes it a true statement.
1 kilogram = 1,000 grams
1 kilogram = 1,000,000 milligrams
Answer:
Friction occurs because no surface is perfectly smooth. Even surfaces that look smooth to the unaided eye make look rough or bumpy when viewed under a microscope.