Answer:
43.7 °C
Explanation:
= Coefficient of linear expansion of brass = 
= Coefficient of linear expansion of steel = 
= Initial length of brass = 31 cm
= Initial length of steel = 11 m
= Total change in length = 3 mm
Total change in length would be


The final temperature is 43.7 °C
Answer:
39.7 m
Explanation:
First, we conside only the last second of fall of the body. We can apply the following suvat equation:

where, taking downward as positive direction:
s = 23 m is the displacement of the body
t = 1 s is the time interval considered
is the acceleration
u is the velocity of the body at the beginning of that second
Solving for u, we find:

Now we can call this velocity that we found v,
v = 18 m/s
And we can now consider the first part of the fall, where we can apply the following suvat equation:

where
v = 18 m/s
u = 0 (the body falls from rest)
s' is the displacement of the body before the last second
Solving for s',

Therefore, the total heigth of the building is the sum of s and s':
h = s + s' = 23 m + 16.7 m = 39.7 m
Answer:
143 °
Explanation:
a ) If d be the distance between slits , λ be wavelength of light used and at angle θ nth dark fringe is formed then
d sinθ = ( 2n+1) λ/2
for first dark fringe
d sinθ = λ/2
d /λ = 1/ 2 sinθ
1 / 2 sin15
= 1.93
b )
For intensity of fringe at angle θ, the relation is
I = I₀ cos²θ
I / I₀ = cos²θ/2
Given I / I₀ =0. 1
0.1 = cos²θ/2
θ/2 = 71.5
θ = 143 °