Answer:
8.4 N/m
Explanation:
m = Mass of block = 4.63 gm
g = Acceleration due to gravity = 
x = Displacement of spring = 0.45 cm
a = Acceleration of subject = 0.832g
k = Spring constant
Force is given by

From Hooke's law

So

The force constant of the spring is 8.4 N/m.
Answer:
Since these two forces are of equal magnitude and in opposite directions, they balance each other. The book is said to be at equilibrium. There is no unbalanced force acting upon the book and thus the book maintains its state of motion. When all the forces acting upon an object balance each other, the object will be at equilibrium; it will not accelerate.
Explanation:
when we placed in the container of real depth assuming = d
if the container filled with liquid A then its apparent depth d' = 7cm
so the refractive index nA = real depth / apparent depth
= d/7cm = 0.1428d
if the container filled with liquid B then its apparent depth d' = 6cm
so the refractive index nB = real depth / apparent depth
= d/6cm = 0.166d
if the container filled with liquid C then its apparent depth d' = 5cm
so the refractive index nC = real depth / apparent depth
= d/5cm = 0.2d
Since the refractive index is inversely proportional to the apparent depth
then the refractive indices are nC > nB > nA
this is simple the word your looking for is 8 letters long and the definition is key to the answer