Suppose you wanted to "pull an Einstein," and create a static universe  in which the gravitational attraction of matter is exac
tly balanced by the gravitational repulsion of dark energy with equation-of-state parameter − 1/ 3 < wq < − 1 and energy density εq.
What is the necessary matter density (εm) required to produce a static universe, expressed in terms of εq and wq?
Will the curvature of this static universe be negative or positive?
What will be its radius of curvature, expressed in terms of εq and wq?
What is the necessary matter density (εm) required to produce a static universe, expressed in terms of εq and wq?
Will the curvature of this static universe be negative or positive?
What will be its radius of curvature, expressed in terms of εq and wq?
2 answers:
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Answer:
v = 9.936 m/s
Explanation:
given,
height of cliff = 40 m
speed of sound = 343 m/s
assuming that time to reach the sound to the player = 3 s
now,
time taken to fall of ball
t = 2.857 s
distance
d = v x t
d = v x 2.875
time traveled by the sound before reaching the player
distance traveled by the wave in this time'
r = 0.143 x 343
r= 49.05 m
now,
we know.
d² + h² = r²
d² + 40² = 49.05²
d =28.387 m
v x 2.875=28.387 m
v = 9.936 m/s
Answer:
9) HIGHER AND LOWER INTESITY, 10) speed of sound must decrease.
11) guitar the strings, flute, 12) In the mountains, 13) sound of a low frequency horn (sub-wofeer)
Explanation:
In this exercise we are asked to complete the sentences.
9) the intensity of the sound is the square of the amplitude, the missing words are
HIGHER INTESITY
LOWER INTENSITY
10) the speed of sound is
v =
and it is also related to temperature
v =
We must be careful since the compressibility modulus (B) changes significantly between the solid, liquid and gaseous states, if we are in the same medium, the speed of sound decreases with increasing density. For a higher density the speed of sound decreases
Also the speed of sound increases with temperature, but its effect is less,
Therefore, by having these two effects in the opposite direction, the change in density is more important, so the speed of sound must decrease.
.
11) when you listen to a guitar the strings resonate with the instrument body
on the flute has a resonance between the blown air and the flute tube
12) When you are in front of a tall object, the sound is reflected and the echo is heard.
In the mountains, in the squares where there is a large object that reflects in sound
13) when we hear the sound of a low frequency horn (sub-wofeer) we feel the vibration of the air, this is an effect of the pressure energy of the sound on our chest