<h3>Question:</h3>
How to find g (acceleration due to gravity)
<h3>Solution:</h3>
We know,
Acceleration due to gravity (g)

where, G = Gravitational constant

M = Mass of the earth

R = Radius of the earth

Putting these values of G, M and R in the above formula, we get

So, the value of acceleration due to gravity is

Hope it helps.
Do comment if you have any query.
Not at all. Density on its own is not sufficient
Answer:
1) P₁ = -2 D, 2) P₂ = 6 D
Explanation:
for this exercise in geometric optics let's use the equation of the constructor
where f is the focal length, p and q are the distance to the object and the image, respectively
1) to see a distant object it must be at infinity (p = ∞)
q = f₁
2) for an object located at p = 25 cm
We can that in the two expressions we have the distance to the image, this is the distance where it can be seen clearly in general for a normal person is q = 50 cm
we substitute in the equations
1) f₁ = -50 cm
2)
= 0.06
f₂ = 16.67 cm
the expression for the power of the lenses is
P = 
where the focal length is in meters
1) P₁ = 1/0.50
P₁ = -2 D
2) P₂ = 1 /0.16667
P₂ = 6 D