C. This is the idea of "black body radiation". Charcoal/carbon is a "perfect black body". Absorbs all radiation. There's a whole host of stuff about this in physics, including, I think, Planck's (Nobel Prize winner) black body radiation theory.
Answer:
t = 12.82s
Explanation:
F = m×a
= (70)×(2)
= 140 N
during the acceleration, the sprinter cover d = 29 m with time:
d = 1/2×at
29 = 1/2×(2)×t^2
t^2 = 29s
t = 5.39s
and attains the velocity of:
v = a×t
= 2×5.39
= 10.77 m/s
Then,to cover the last x = 80 m with a speed of 10.77 m/s in time:
t = x/v
= 80/10.77
= 7.43s
Therefore, it will take the sprinter 7.43 + 5.39 = 12.82s
Answer:
the wavelength λ of the light when it is traveling in air = 560 nm
the smallest thickness t of the air film = 140 nm
Explanation:
From the question; the path difference is Δx = 2t (since the condition of the phase difference in the maxima and minima gets interchanged)
Now for constructive interference;
Δx= 
replacing ;
Δx = 2t ; we have:
2t = 
Given that thickness t = 700 nm
Then
2× 700 =
--- equation (1)
For thickness t = 980 nm that is next to constructive interference
2× 980 =
----- equation (2)
Equating the difference of equation (2) and equation (1); we have:'
λ = (2 × 980) - ( 2× 700 )
λ = 1960 - 1400
λ = 560 nm
Thus; the wavelength λ of the light when it is traveling in air = 560 nm
b)
For the smallest thickness 
∴ 



Thus, the smallest thickness t of the air film = 140 nm