Answer:
The moment of inertia about the rotation axis is 117.45 kg-m²
Explanation:
Given that,
Mass of one child = 16 kg
Mass of second child = 24 kg
Suppose a playground toy has two seats, each 6.1 kg, attached to very light rods of length r = 1.5 m.
We need to calculate the moment of inertia
Using formula of moment of inertia


m = mass of seat
m₁ =mass of one child
m₂ = mass of second child
r = radius of rod
Put the value into the formula


Hence, The moment of inertia about the rotation axis is 117.45 kg-m²
Answer:
distance between the dime and the mirror, u = 0.30 m
Given:
Radius of curvature, r = 0.40 m
magnification, m = - 2 (since,inverted image)
Solution:
Focal length is half the radius of curvature, f = 
f = 
Now,
m = - 
- 2 = -
= 2 (2)
Now, by lens maker formula:


v =
(3)
From eqn (2):
v = 2u
put v = 2u in eqn (3):
2u = 
2 = 
2(u - 0.20) = 0.20
u = 0.30 m