Good luck with solving this
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
Answer:
h = 20 m
Explanation:
height (h) = 10 m
potential energy (PE) = 50 J
kinetic energy (KE) = 50 J
what is the maximum height reached by the ball
- At 10 meters above the ground potential energy (PE) = 50 J
mgh = 50
recall that height (h) = 10
mg (10) = 50
mg = 5 .....equation 1
- The total energy of the system at 10 meters is given as PE + KE = 100 Joules. From the conservation of energy the total energy in the system still remains the same at the maximum height, this is because energy can neither be created nor destroyed but can be transformed from one form to another.
- At the maximum height the velocity (v) of the system is 0, which means all its kinetic energy (KE) is converted to potential energy. Therefore the system consist only of potential energy.
KE + PE = 100
+ mgh = 100 J
velocity (v) = 0 at maximum height therefore
0 + mgh = 100
mgh = 100
recall that mg = 5 from equation 1, therefore
5h = 100
h = 20 m
Answer:
dynamic im pretty sure that's it
Answer:
4.28 s
Explanation:
after two seconds (2 s) His friends is
d = 3.5 m/s x 2 s = 7 meter ahead.
in this state, a bicylist start from initial velocity vo = 0 m/s and accelerat 2.4 m/s²
then, when bicylist reach his friend
t friend = t bicyclist = t
d bicylist = d friend + d
-------
d friend = 3.5 . t
d bicylist = vo . t + ½ a t²
d friend + d = vo . t + ½ a t²
3.5 t + 7 = 0 . t + ½ . 2.4 . t²
3.5 t + 7 = 1.2 t²
0 = 1.2 t² - 3.5 t - 7
t = -1.363 and t = 4.28
take the positive one