The frequency is how many per second:
(6 swings)/(30 sec) = (6/30) swing/sec = 0.2 per sec = 0.2 Hz .
The period is how long each one takes, or seconds per swing.
It's exactly the flip of frequency.
So we could just take the frequency, flip it, and find 1 / 0.2 ,
but let's do it the long way:
(30 sec) / (6 swings) = (30/6) sec/swing = 5 seconds .
Well, I'll try to write the formula in a way that's not confusing,
but I'm afraid it might be slightly confusing anyway.
When you're working with dB, the basic rule is
A change of 10 dB means either multiplying or dividing by 10 .
Multiply something by 10 ==> it increases by 10 dB.
Divide something by 10 ==> it decreases by 10 dB.
It turns out that another way to write all of this is . . .
An increase of 10 dB ===> multiply the original amount by 10¹
An increase of 20 dB ===> multiply the original amount by 10²
An increase of, say, 7 dB ===> multiply the original amount by 10⁰·⁷
A decrease of 10 dB ===> multiply the original amount by 10⁻¹
A decrease of 30 dB ===> multiply the original amount by 10⁻³
A decrease of, say, 13 dB ===> multiply the original amount by 10⁻¹·³
This question says: The sound increases by 5 dB .
That means the original 'intensity' or 'power' of the sound
is multiplied by
10⁰·⁵ = √10 = about 3.162 (rounded) .
From the choices listed, the closest one is (c).
40.64 cm is the answer to your question.
Oxygen has Atomic number 8 so all isotopes have 8 protons and 8 electrons.
So the number of neutrons in Oxygen-18 = 18 - 8 = 10.
Option B is the correct one.
bonded pairs of electrons, lone pairs of electrons.
