Answer:
392
Explanation:
According to the law of conservation of energy, energy cannot vanish,so the lost potential energy must be converted into another form of energy (in this case, Kinetic Energy).
(mass*g*height)-(mass*g*halfway height)=(2*9.8*40)-(2*9.8*20)
784-392=392
This makes sense because since the rock has fallen halfway, half of its potential energy has become kinetic energy. Once the rock reaches a height of 0 Meter, all of its potential energy will be kinetic energy.
The answer is c electrostatic repulsion between nuclei
Answer:

Explanation:
All the gases at the same temperature and mass have the same average kinetic energy.
If the masses were different, then the different gases will have different velocities. If the temperature was higher then there would be a greater motion, if the temperature was lower, then there would be less motion.
Answer:
i think multipling 30 to the 40
30 × 40 = 1200ppt