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

Physics

1 answer:

PSYCHO15rus [73]4 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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Acharged particle moving through a magnetic field at right angles to the field with a speed of 36.2 m/s experiences a magnetic f

Arada [10]

Answer:

7212.3 N

Explanation:

F = 7.38 x 10^4 N, v = 36.2 m/s

Let b be the strength of magnetic field and charge on the particle is q.

F = q v B Sin theta

Here theta = 90 degree

7.38 x 10^4 = q x 36.2 x B x Sin 90

q B = 2038.7 .....(1)

Now, theta = 17 degree, v = 12.1 m/s

F = q v B Sin theta

F = 2038.7 x 12.1 x Sin 17 ( q v = 2038.7 from equation (1)

F = 7212.3 N

3 0

3 years ago

A water pump draws about 9 A when connected to 240 V. What is the cost (with electrical energy at 13 cents per kWh) of running t

Fiesta28 [93]

Answer:

4.49 dollars

Explanation:

i = 9 A, V = 240 V, t = 16 h

Energy = V x i x t = 240 x 9 x 16 = 34560 W h = 34.56 kWh

The cost of 1 kWh is 13 cents.

Cost of 34.56 kWh = 13 x 34.56 = 449.28 cents = 449.28 / 100 = 4.49 dollars

8 0

4 years ago

A man is sitting on a chair with wheels. He grabs a 2.1 kg book from the desk and throws

geniusboy [140]

The speed of the man and the chair after the book is thrown is 0.2 m/s.

The given parameters:

mass of the book, m₁ = 2.1 kg
speed of the book, u₁ = 7.2 m/s
mass of the man, M = 70 kg
mass of the book, m = 9.2 kg

The total mass of the man and the book is calculated as follows;

m₂ = 70 kg + 9.2 kg

m₂ = 79.2 kg

The speed of the man and the chair after the book is thrown is determined by applying the principle of conservation of linear momentum;

$m_1 u_1 = m_2u_2\\\\u_2 = \frac{m_1u_1}{m_2} \\\\u_2 = \frac{2.1 \times 7.2}{79.2} \\\\u_2 = 0.2 \ m/s$