When it falls though a vaccum,it is subjected to only one external force,the gravitational force.
Efficiency = (useful output) / (input). For this device, it's 0.1 or 10%. The correct answer isn't listed as one of the choices.
Bag of feathers because it weighs the least
The correct answer is B. Nitrogen
The number of electrons in a neutral atom is equal to the number of protons. The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus. The number of neutrons is equal to the difference between the mass number of the atom (M) and the atomic number. Therefore, it is true!