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kifflom [539]
4 years ago
5

Dark energy is an unexplained force that is causing _____. stars to explode the expansion of the universe to accelerate the univ

erse to contract galaxies to group together
Physics
2 answers:
GalinKa [24]4 years ago
3 0
The best choice would be the second statement. Dark energy is an unexplained force that is causing the expansion of the universe to accelerate. It is an unknown form of energy which is the most accepted hypothesis during the 1990s to explain the observations that the universe is expanding at a rate that is accelerating.
Tatiana [17]4 years ago
3 0

Answer:

Dark energy is an unexplained force that is causing the expansion of the universe to accelerate.

Explanation:

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If the work function of a material is such that red light of wavelength 700 nm just barely initiates the photoelectric effect, w
marishachu [46]

Answer:

2.13 x 10^-19 J or 0.53 eV

Explanation:

cut off wavelength, λo = 700 nm = 700 x 10^-9 m

λ = 400 nm = 400 x 10^-9 m

Use the energy equation

E = \frac{h c}{\lambda _{o}}+K

Where, K be the work function

\frac{h c}{\lambda} = \frac{h c}{\lambda _{o}}+K

K =hc\left ( \frac{1}{\lambda } -\frac{1}{\lambda _{0}}\right )

K =6.63\times 10^{-34}\times 3\times 10^{8}\left ( \frac{1}{4\times 10^{-7} } -\frac{1}{7\times 10^{-7}}\right )

K = 2.13 x 10^-19 J

K = 0.53 eV

3 0
3 years ago
Determine the force p required to (a) raise and (b) lower the 40-kg cylinder at a slow, steady speed. the coefficient of frictio
Norma-Jean [14]

Answer:

T - M g - Ff = M a     describes the acceleration of the object

T = M g + Ff      if the object moves at constant speed  (a = zero)

Ff = μ M g = .3 * 40 * 9.8 = 118 N     the force of friction

Ff will be in a direction opposite to the motion

M g = 40 kg * 9.8 m/s = 392 N

a) T = M g + Ff   for an object moving upwards

T = 392 + 118 = 510 N

b) T = M g - Ff     for an object moving downwards

T = 392 - 118 = 274 N

8 0
2 years ago
b) The distance of the red supergiant Betelgeuse is approximately 427 light years. If it were to explode as a supernova, it woul
Nat2105 [25]

Answer:

b) Betelgeuse would be \approx 1.43 \cdot 10^{6} times brighter than Sirius

c) Since Betelgeuse brightness from Earth compared to the Sun is \approx 1.37 \cdot 10^{-5} } the statement saying that it would be like a second Sun is incorrect

Explanation:

The start brightness is related to it luminosity thought the following equation:

B = \displaystyle{\frac{L}{4\pi d^2}} (1)

where B is the brightness, L is the star luminosity and d, the distance from the star to the point where the brightness is calculated (measured). Thus:

b) B_{Betelgeuse} = \displaystyle{\frac{10^{10}L_{Sun}}{4\pi (427\ ly)^2}} and B_{Sirius} = \displaystyle{\frac{26L_{Sun}}{4\pi (26\ ly)^2}} where L_{Sun} is the Sun luminosity (3.9 x 10^{26} W) but we don't need to know this value for solving the problem. ly is light years.

Finding the ratio between the two brightness we get:

\displaystyle{\frac{B_{Betelgeuse}}{B_{Sirius}}=\frac{10^{10}L_{Sun}}{4\pi (427\ ly)^2} \times \frac{4\pi (26\ ly)^2}{26L_{Sun}} \approx 1.43 \cdot 10^{6} }

c) we can do the same as in b) but we need to know the distance from the Sun to the Earth, which is 1.581 \cdot 10^{-5}\ ly. Then

\displaystyle{\frac{B_{Betelgeuse}}{B_{Sun}}=\frac{10^{10}L_{Sun}}{4\pi (427\ ly)^2} \times \frac{4\pi (1.581\cdot 10^{-5}\ ly)^2}{1\ L_{Sun}} \approx 1.37 \cdot 10^{-5} }

Notice that since the star luminosities are given with respect to the Sun luminosity we don't need to use any value a simple states the Sun luminosity as the unit, i.e 1. From this result, it is clear that when Betelgeuse explodes it won't be like having a second Sun, it brightness will be 5 orders of magnitude smaller that our Sun brightness.

4 0
3 years ago
An object's
shusha [124]

The planet of an item will remain constant across the planet, but if you give it more mass, the gravitational force increases while the acceleration due to gravity remains constant.

<h3 /><h3>What is the difference between mass and weight?</h3>

The mass of the body is defined as the amount of matter a body has. It is denoted by m and its unit is kg. Mass is the quantity on which a lot of physical quantity depends.

Weight is defined as the amount of force an object exerts on the surface. It is given as the product of mass and the gravitational pull.

Mass is an independent quantity it never depends on the other. While weight is a dependent quantity that depends upon the gravitational pull.

The value of gravitational pull is different in the different parts of the universe. For example, on the earth, the value of gravitational acceleration is 9.81 m/sec².While on the moon it is g/6.

Weight is change according to the place or surrounding while the mass of the body is constant everywhere.

The planet of an item will remain constant across the cosmos, but if you give it more mass, the gravitational force increases while the acceleration of gravity remains constant.

If a planet's gravity weakens, the weight of that planet will likewise be altered. With an increase in mass, weight also rises.

Hence, the gravitational force increases while the acceleration due to gravity remains constant for the given case.

To learn more about the mass refer to the link;

brainly.com/question/19694949

#SPJ1

3 0
2 years ago
What is velocity and it’s SI Unit?
svp [43]

Answer:

Velocity is the displacement (change In position of an an object it is similar to distance ) divided by the time taken. SI unit m/s (metre per second)

3 0
3 years ago
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