The correct answer of the given question above would be the first option. The statement that is true concerning atoms is that, atoms are made of even smaller substances called subatomic particles. Subatomic particles include neutrons, protons, electrons and atomic nuclei. Hope this answer helps.
Answer:
Explanation:
a is the acceleration
μ is the coefficient of friction
Acceleration of the object is given by

Velocity at the bottom

after travelling 4m , its velocity becomes 0



Coefficient of kinetic friction
μ = F/N

Therefore, the Coefficient of kinetic friction is 0.31