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NeTakaya
4 years ago
9

Which is one piece of information that astronomers use to calculate the age of the universe?

Physics
1 answer:
Valentin [98]4 years ago
8 0

Answer:

  • the age of the oldest stars
  • patterns of background radiation
  • how fast distant galaxies are moving away from us

Explanation:

According to the NASA, astronomers can estimate how old the universe is by comparing the age of the oldest stars and the rate of expansion of the universe. The rate of expansion of the universe is based on the Big Bang theory and it states that our universe is continuously expanding since it first developed. Astronomers measure Cosmic Microwave Background radiation resulting from the Big Bang.

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The diagram shows waves of sound travelling through the air. By which factor is the sound intensity decreased at 3 meters?
SIZIF [17.4K]
The diagram is missing; however, we know that the intensity of a sound wave is inversely proportional to the square of the distance from the source:
I(r)= \frac{1}{r^2}
where I is the intensity and r is the distance from the source.

We can assume for instance that the initial distance from the source is r=1 m, so that we put 
I= \frac{1}{r^2}= \frac{1}{(1)^2}=1
The intensity at r=3 m will be
I= \frac{1}{r^2}= \frac{1}{(3)^2}= \frac{1}{9}
Therefore, the sound intensity has decreased by a factor 1/9.
8 0
3 years ago
Read 2 more answers
If a 9 V battery with 4 Ω contact resistance is used and the relay has 80 Ω and the wire has 10 Ω/mile, what is the maximum tele
Sedaia [141]

Answer:

Telegraph distance will be 9.6 mile

Explanation:

We have given the voltage V = 9 volt

Contact resistance = 4 ohm

Relay resistance = 80 ohm

And wire has a resistance = 10 ohm/mile

We have given the current = 50 mA =0.05 A

According to ohm's law R=\frac{V}{I}=\frac{9}{0.05}=180ohm

So the resistance of wire = 180-4-80=96 ohm

So the length of the telegraph distance will be \frac{96}{10}=9.6mile

4 0
4 years ago
What is a Homonym for a type of cloak?
blsea [12.9K]

Answer:

In both cases, the sound and spelling are the same, and only the definition changes. Here are 30 more examples of homonyms. Note that some homonyms have more than two meanings (for example, "tender" can also mean sensitive, easily chewed, or even refer to chicken strips), but to keep things simple we've only included two in our homonyms list:

8 0
3 years ago
A machinist turns the power on to a grinding wheel, which is at rest at time t = 0.00 s. The wheel accelerates uniformly for 10
IRINA_888 [86]

Complete Question:

A machinist turns the power on to a grinding wheel, which is at rest at time t = 0.00 s. The wheel accelerates uniformly for 10 s and reaches the operating angular velocity of 25 rad/s. The wheel is run at that angular velocity for 37 s and then power is shut off. The wheel decelerates uniformly at 1.5 rads/s2 until the wheel stops. In this situation, the time interval of angular deceleration (slowing down) is closest to

Answer:

t= 16.7 sec.

Explanation:

As we are told that the wheel is accelerating uniformly, we can apply the definition of angular acceleration to its value:

γ = (ωf -ω₀) / t

If the wheel was at rest at t-= 0.00 s, the angular acceleration is given by the following equation:

γ = ωf / t = 25 rad/sec / 10 sec = 2.5 rad/sec².

When the power is shut off, as the deceleration is uniform, we can apply the same equation as above, with ωf = 0, and ω₀ = 25 rad/sec, and γ = -1.5 rad/sec, as follows:

γ= (ωf-ω₀) /Δt⇒Δt = (0-25 rad/sec) / (-1.5 rad/sec²) = 16.7 sec

8 0
3 years ago
41. City A lies 30 km directly south of city B. A bus, beginning at city A travels 50 km at 37° north of east to reach city C. H
Nana76 [90]

Answer:

B) 40 km West

Explanation:

Let position of B is origin so with respect of City B the position of A is given as

r_A = 30 km south of city B

now Bus starts from City A and travels a distance of 50 km at 37 degree North of East to reach city C

so it is

r_{CA} = 50(cos37\hat i + sin37 \hat j)

r_{CA} = 40\hat i + 30\hat j

now the position of C is given with respect to A

in order to find the position of C with respect to B we can say

r_C = r_{CA} + r_A

r_C = 40\hat i + 30\hat j + (-30 \hat j)

r_C = 40 \hat i

so in order to reach at city B from city C bus has to travel 40 km towards West

7 0
3 years ago
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