Answer: 20
Explanation: Mass number is the number of neutrons plus the number of protons. 8 + 12 gives 20.
Answer:
So coefficient of kinetic friction will be equal to 0.4081
Explanation:
We have given mass of the block m = 0.5 kg
The spring is compressed by length x = 0.2 m
Spring constant of the sprig k = 100 N/m
Blocks moves a horizontal distance of s = 1 m
Work done in stretching the spring is equal to 
This energy will be equal to kinetic energy of the block
And this kinetic energy must be equal to work done by the frictional force
So 


So coefficient of kinetic friction will be equal to 0.4081
D is the point where the planet moves the fastest. This is because it is in the perihelion, where the planet is moving at it’s fastest pace
2.27 mps repeating.
This is the last question ill ever answer here. Thanks for being the last.