Answer:
λ = 0.4 x 10⁻⁶ m = 400 nm
Explanation:
The relationship between frequency, wavelength and speed of an electromagnetic wave is given as follows:

where,
c = speed of light = 3 x 10⁸ m/s
f = frequency of the light wave = 7.5 x 10¹⁴ Hz
λ = wavelength of the light = ?
Therefore,

<u>λ = 0.4 x 10⁻⁶ m = 400 nm</u>
 
        
             
        
        
        
Answer:
 y = 138.96 m
Explanation:
The angle subtended by the moon is the mean of the angle of the arc between the two most extreme points of the moon, we can see that the angle is very small, so we can approximate this arc to a straight line and then use the trigonometric relationships
          sin θ = y / L
where L = 15.9 10³ m and θ = 8.74 10⁻³ rad
           y = L sin θ
           y = 15.9 10³ sin (8.74 10⁻³)
          y = 15.9 10³    0.0087399
          y = 138.96 m
 
        
             
        
        
        
The answer is 9.8, did this last year in AP Science
 
        
             
        
        
        
I believe you got it correct already