Answer:
C : Steel
Explanation:
Steel is manufactured and not made by the Earth itself
To rise the bird from your finger to make it look real.
499.15 is lines per millimeter needed in a diffraction grating if the lines are to be resolved in the second-order spectrum with a beam of width 0.10 mm.
the wave length of the sodium spectrum are λ1 = 589.0 nm and λ2 =589.59 nm
The resolving power of the grating is R = λ/Δλ =Nm.
Thus, the total number of lines needed on the grating to resolve the wavelengths in order m is
For the sodium doublet in the first order, N = λ /m(Δλ)
where λ = 589.0 nm , Δλ = 589.59 nm -589.0 nm = 0.59 nm
m = 2
The minimum number of lines in the grating
N = [589.0 nm] / [(2)( 0.59 nm )] = 499.15
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The question appears to be incomplete.
I assume that we are to find the coefficient of static friction, μ, between the desk and the book.
Refer to the diagram shown below.
m = the mass of the book
mg = the weight of the book (g = acceleration due to gravity)
N = the normal reaction, which is equal to
N = mg cos(12°)
R = the frictional force that opposes the sliding down of the book. It is
R = μN = μmg cos(12°)
F = the component of the weight acting down the incline. It is
F = mg sin(12°)
Because the book is in static equilibrium (by not sliding down the plane), therefore
F = R
mg sin(12°) = μmg cos(12°)
Therefore, the static coefficient of friction is
μ = tan(12) = 0.213
Answer: μ = 0.21 (nearest tenth)