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Komok [63]
3 years ago
11

1. Define dark matter and dark energy, and clearly distinguish between them. What types of observations have led scientists to p

ropose the existence of each of these unseen influences?
Physics
1 answer:
Vlada [557]3 years ago
7 0

Explanation:

Dark Energy is a property of the entire universe. And the universe is roughly made up of 68% of this dark energy whereas dark matter makes up 27% of the universe matter.

   The influence of the dark matter shows in the individual galaxies whereas dark energy acts only on the entire universe. dark matter is responsible for the gravity effect on the plants and the heavenly bodies which produces gravity force. But the dark energy is known as the anti gravity force as it is responsible for the expansion of the universe. Dark matter attracts and produces an attractive force while dark energy repels and produces a repulsive force.

          Scientist believe that they exists to account for the very fact that gravity holds all the heavenly bodies and the galaxies together. They are even responsible for the fluctuation in Cosmic Microwave background. Researchers and scientist firmly believe that all the visible matter that exists may not have enough gravitational pull to hold everything together in the galaxies. And also the expanding universe strongly proves that dark energy exists in the universe.

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When four quadruplets cry simultaneously, how many decibels greater is the sound intensity level than when a single one cries?
Ket [755]

Answer:

Explanation:

Assume that a single baby cries at X db

4 babies crying would be X + 10log₁₀(4) = X + 6 db

8 0
2 years ago
A circuit is built based on the circuit diagram shown. What is the current in the 50 Ω resistor
In-s [12.5K]

Answer:

1.2 A

Explanation:

From the diagram attached, The three resistors are parallel because the each ends of the resistors are connected together. Since they are in parallel, the voltage across each resistor is the same. The voltage source connected in parallel to the resistors is 60 V. Therefore the voltage across the 50 Ω resistor is 60 V. Using ohm law:

Voltage (V) = Current (I) × Resistance (R)

V = IR

I = V/R

I = 60 V/ 50 Ω

I = 1.2 A

The current in the 50 Ω resistor is 1.2 A

5 0
3 years ago
A flatbed truck is supported by its four drive wheels, and is moving with an acceleration of 6.3 m/s2. For what value of the coe
Levart [38]

Answer:

Coefficient of static friction will be equal to 0.642  

Explanation:

We have given acceleration a=6.3m/sec^2

Acceleration due to gravity g=9.8m/sec^2

We have to find the coefficient of static friction between truck and a cabinet will

We know that acceleration is equal to a=\mu g, here \mu is coefficient of static friction and g is acceleration due to gravity

So \mu =\frac{a}{g}=\frac{6.3}{9.8}=0.642

So coefficient of static friction will be equal to 0.642

3 0
3 years ago
A light-rail commuter train accelerates at a rate of 1.35 m/s. D A 33% Part (a) How long does it take to reach its top speed of
Dennis_Churaev [7]

Answer:

a) 17.49 seconds

b) 13.12 seconds

c) 2.99 m/s²

Explanation:

a) Acceleration = a = 1.35 m/s²

Final velocity = v = 85 km/h = 85\frac{1000}{3600}=23.61\ m/s

Initial velocity = u = 0

Equation of motion

v=u+at\\\Rightarrow 23.61=0+1.35t\\\Rightarrow t=\frac{23.61}{1.35}=17.49\ s

Time taken to accelerate to top speed is 17.49 seconds.

b) Acceleration = a = -1.8 m/s²

Initial velocity = u = 23.61\ m/s

Final velocity = v = 0

v=u+at\\\Rightarrow 0=23.61-1.8t\\\Rightarrow t=\frac{23.61}{1.8}=13.12\ s

Time taken to stop the train from top speed is 13.12 seconds

c) Initial velocity = u = 23.61 m/s

Time taken = t = 7.9 s

Final velocity = v = 0

v=u+at\\\Rightarrow 0=23.61+a7.9\\\Rightarrow a=\frac{-23.61}{7.9}=-2.99\ m/s^2

Emergency acceleration is 2.99 m/s² (magnitude)

6 0
3 years ago
Which of the following choices defines energy in scientific terms?
snow_tiger [21]
1) B. Energy is the ability to do work

2) C. Energy is conserved, it just goes from one form to another.

3) Work = Force x displacement
= 300 x 100 = 30,000 Joules

4) leaning a brick because no displacement is taking place.

5) They change the amount/strength or direction of the force needed.

6) Less force is needed and applied over a longer distance.

7) Heat is the flow of thermal energy from one object to another.
8 0
3 years ago
Read 2 more answers
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