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Hoochie [10]
3 years ago
12

What is dark energy and what evidence do astronomers have that it is an important component of the universe?

Physics
1 answer:
PSYCHO15rus [73]3 years ago
8 0

Answer:

The existance of dark energy was suggested to help explain measurements, using Type Ia supernovae as distance indicators, that the expansion of the universe is speeding up and its acceleration requires a source of energy. Scientists suggested that It may be a new form of energy for which there is not yet a theoretical explanation. quantum mechanics predict that it may be the vacuum energy associated with "empty" space itself.

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What are the two forces that are acting on the skydiver? What is
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Answer:

Gravity provides a downward force, resulting in the diver going downward. They speed up like any falling object would, the pull of gravity is a dominant force. (There is a drag force – as a result of moving through the air.)

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3 years ago
Arrange the balls in order from greatest amount of gravitational potential energy to least.
Ratling [72]
All of them have the same potential energy <span />
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3 years ago
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What is the frequency of a microwave of wavelength 3cm?
navik [9.2K]

Frequency = (speed) / (wavelength)

Speed = 3 x 10⁸ m/s

Wavelength = 3 cm = 0.03 m

Frequency = (3 x 10⁸  m/s) / (0.03 m)

Frequency = (3 x 10⁸ / 0.03) (m / m-s)

Frequency =  1 x 10¹⁰ Hz (10 Gigahertz)

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3 years ago
Why does a gymnast rub powder on his hands before exercising on a set of parallel bars? (I need a scientific answer)
dlinn [17]

<u>Answer</u>

To increase friction for a better grip.

<u>Answer</u>

Most human beings do sweat hands especially on the palm. When this happens the person will not have a good grip of heavy objects because they will slide/slip from the hand.

<em>By applying the powder, you are trying to make the hand dry hence increasing the friction for a better grip. </em>

If the gymnast doesn't do this the parallel bars may slip from the hands and injure himself or herself.

4 0
3 years ago
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Two identical sticky masses m are moving in the xy-plane, with their momenta at an angle of φ with one another. They are each mo
postnew [5]

Answer:

ucosφ=-v2cosθ2\\\\φ=cos^{-1} (\frac{-v2cosθ2}{cosφ} )

Explanation:

Two identical sticky masses m are moving in the xy-plane, with their momenta at an angle of φ with one another. They are each moving at the same speed v when they collide at the origin of the coordinates and stick together. After the collision, the masses move at an angle −θ2 with respect to the +x axis at speed v2 .1. What was the angle φ?

from the principle of momentum

In a system of colliding bodies,we know that the total momentum before collision will equal to the total momentum after collision.

Take note that momentum is the product of mass and velocity

momentum before collision=momentum after collision

mass, m

u=initial velocity of the identical masses

v2=the common velocity after the collision

Note that the collision is inelastic , since they both moved with the same velocity

umcosφ+umcosφ=(m+m)v2cos−θ2

2mucosφ=2mv2cos−θ2

ucosφ=-v2cosθ2\\\\φ=cos^{-1} (\frac{-v2cosθ2}{cosφ} )

8 0
3 years ago
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