I can't remember how to solve this kind of problem.
So, in desperation, I take a hard look at the units.
I do remember that electric field is measured in volts per meter,
and 1 volt/meter means 1 newton/coulomb. And there it is !
The problem has a quantity of [newtons] and a quantity of [coulombs]
in it. If I divide those, the quotient will be [newton/coulomb], and THAT's
electric field strength !
(3.0 x 10⁻⁹ N) / (1.25 x 10⁻¹⁹ C)
= 2.4 x 10¹⁰ N / C
= 2.4 x 10¹⁰ volts/meter .
<h2>The intensity of siren is 0.015 W m⁻²</h2>
Explanation:
The intensity of sound is inversely proportional to the square of distance between source and the observer .
Thus Intensity at a distance 25 m is I₁ ∝ 
I
Similarly the intensity at a distance 50 m is I₂ ∝ 
II
Dividing II by I , we have
= 
= 
= 
Thus I₂ = x 0.06 = 0.015 W m⁻²
I would say it’s “donating” so giving up...
1. I think you should compare diagrams of moon phases from the textbook to diagrams of moon phases online. Because if you pick D it will take to long and C will help you out whith 3 different things to look at.
2. The moon changes in appearances from the perspective of people on earth because it's revolving around the planet and the earth is revolving around the sun, so A. Hoped this helped.
