Answer:
distance is 13 m for 100 dB
distance is 409 km for 10 dB
Explanation:
Given data
distance r = 2.30 m
source β = 115 dB
to find out
distance at sound level 100 dB and 10 dB
solution
first we calculate here power and intensity and with this power and intensity we will find distance
we know sound level β = 10 log(I/
) ......................a
put here value (I/) = 10^−12 W/m² and β = 115
115 = 10 log(I/10^−12)
so
I = 0.316228 W/m²
and we know power = intensity × 4π r² ...............b
power = 0.316228 × 4π (2.30)²
power = 21.021604 W
we know at 100 dB intensity is 0.01 W/m²
so by equation b
power = intensity × 4π r²
21.021604 = 0.01 × 4π r²
so by solving r
r = 12.933855 m = 13 m
distance is 13 m
and
at 10 dB intensity is 1 × 10^–11 W/m²
so by equation b
power = intensity × 4π r²
21.021604 = 1 × 10^–11 × 4π r²
by solving r we get
r = 409004.412465 m = 409 km
When we jump from the truck and accelerate towards the earth surface, the earth also accelerates towards us but it's acceleration is very negligible.
To find the answer, we need to know about the acceleration of earth due to the gravitational attraction.
<h3>What's the gravitational force between the earth and a person?</h3>
- Gravitational attraction force is GMm/r² between the earth and a person.
- M= mass of the earth
m= mass of the person
r= separation between them.
<h3>What's the acceleration of the earth towards the person when he jumps from a truck?</h3>
- According to Newton's second law, Force = M×acceleration
- Acceleration= Force / M
- Here, Force = GMm/r²,
so acceleration of earth= Gm/r²
- As this acceleration is very small, so we can't notice it.
Thus, we can conclude that the earth also accelerates towards us.
Learn more about the gravitational force here:
brainly.com/question/72250
#SPJ4
The answer is c because the farther apart they are the greater there gravity is
The formula that is applicable here is E = kQ/r^2 in which the energy of attraction is proportional to the charges and inversely proportional to the square of the distance. In this case,
kQ1/(r1)^2 = kQ2/(r2)^2 r1=l/3, r2=2l/3solve Q1/Q2
kQ1/(l/3)^2 = kQ2/(2l/3)^2 kQ1/(l^2/9) = kQ2/(4l^2/9)Q1/Q2 = 1/4
