The fundamental cause of a variable star's change in luminosity is that the star's _____ is changing.

Answers

Answer 1
The radius is changing !

Related Questions

Describe what you think energy is in physics and what does it do.

Answers

In Physics, energy can be defined as the ability and capacity to do work by an object or physical body.

What is energy?

In Physics, energy can be defined as the ability to do work. Thus, energy must be possessed or transferred to a physical object (body) before it can be used in doing a work or heating a system.

The types of energy.

Generally, there are two (2) main types of energy and these are;

Potential energy (P.E): it is an energy that is possessed by an object or body due to its height (position) above the Earth surface.Kinetic energy (K.E): it is an energy possessed by an object or body due to its motion.

For example, you require a sufficient amount of energy to move a crate of egg across a given distance.

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Answer:. It may exist in potential, kinetic, thermal, electrical, chemical, nuclear, or other various forms. There are, moreover, heat and work—i.e., energy in the process of transfer from one body to another. ... All forms of energy are associated with motion.

Explanation:. It may exist in potential, kinetic, thermal, electrical, chemical, nuclear, or other various forms. There are, moreover, heat and work—i.e., energy in the process of transfer from one body to another. ... All forms of energy are associated with motion.

How are the two types of power plants similar how are they different

Answers

Answer:

iIn a nuclear plant, the heat source is from the nuclear reaction whereas in a thermal power plant it is from the combustion of coal. The difference is in the inlet steam parameters to the turbine in a nuclear plant. Thermal power plants use steam at superheated conditions. ... The nuclear plant uses a 'wet steam turbine'.

Explanation:

The heat source in a nuclear power plant is the nuclear reaction, whereas the heat source in a thermal power plant is coal combustion. The difference is in the turbine's input steam characteristics.

What is a power plant?

Power plant is an industrial structure that generates electricity. The majority of power plants are linked to the electrical grid.

Nuclear power bare a form of thermal power plant. You have a reactor where fission takes place and heat is generated, a heat exchanger that transports this heat to where it is needed.

Thermal power plant equipment converts this heat into electric energy, usually via a steam turbine.

The reactor, heat exchanger, and thermal conversion technology all have different designs and technologies, but the overall architecture is quite similar to other types of thermal power plants.

The heat source in a nuclear power plant is the nuclear reaction, whereas the heat source in a thermal power plant is coal combustion. The difference is in the turbine's input steam characteristics.

Hence, the two types of power plants differ in  difference is in the turbine's input steam characteristics.

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please help meee please please

Answers

Answer:

I think it's c but don't know for sure

a mass of 7.5kg has a weight of 30n on a certain planet calculate the acceleration due to gravitt on this planet

Answers

Answer:

Acceleration due to gravity on a certain planet = 4 m/s²

Explanation:

According to the question,

Weight = 30 N

Mass = 7.5 kg

Let acceleration due to gravity be 'a'

Formula:

Weight = Mass × Acceleration due to gravity

30 = 7.5 × a

a = 30/7.5

a = 4 m/s²

Example 4.16
An object of mass 3 kg rests on a plane. The coefficient of static friction and that of kinein
friction are given by Hs = 0.3 and pk = 0.2.
The plane is inclined at angle o to the horizontal.
(i) Find the maximum value of 0 for which the object remains at rest on the plane.
(ii) Find the acceleration of the object if it started sliding from rest down the plane at
angle Omax to the horizontal.
(ii) How long does it take the object to move, from rest, a distance of Imetre under the
conditions of (ii).

Answers

Answer:

Explanation:

(i) μs = F/N = mgsinθ/mgcosθ = tanθ

  tanθ = 0.3

  θ = 16.7°

(ii) a = F/m

    a = (mgsinθ - (μk)mgcosθ) / m

    a = g(sinθ - (μk)cosθ)

    a = 9.8(sin16.7 - (0.2)cos16.7)

    a = 0.94 m/s²

(iii) s = ½at²

     t = √(2s/a)

     t = √(2(1)/0.94)

     t = 1.5 s

electric field due to on the surface of the charge sphere​

Answers

Explanation:

static electricity draws energy

What is the neutron number for 75 32Ge?

Answers

Answer:

If the mass of geranium is 75 and the atomic number is 32 then it must have

N = 75 -32 = 43 neutrons

Sam wants to get a refrigerator into a moving truck. He chooses to use a ramp to accomplish the task that is 25 meters long. If the fridge weighs 250 N, what force will Sam need to use on the ramp to get the fridge into the 3 m high truck bed?​

Answers

Answer:

Explanation:

Ignoring friction and assuming one ramp end rests on level ground.

gravity acceleration acting parallel to the ramp is gsinθ.

F = mgsinθ

mg = 250 N,  sinθ = 3/25

F = 250(3/25)

F = 30 N

A 25 meter long ramp strong enough to hold a person plus a 250 N refrigerator would weigh much more than 250 N.

Light from the Sun takes about 8.0 min to reach Earth. How far away is the Sun? Answer in scientific notation

Answers

z = 149.4 million km.
Explanation:
z = c * t
if you know the time that light takes to reach us then you can calculate the distance to that object and vice versa.
In the above equation,

z is the distance to the object.
t is the time light takes from the object to reach us

c is the speed of light which is always constant about 300,000 km/ sec.
The time light takes to reach us from the Sun is about 8.3 minutes.

z = 8.3 * 300,000

Note that the speed of light is in units of km/ sec so we will have to convert minutes into seconds.
1 minute = 60 seconds

8.3 minutes = 8.3 * 60

8.3 minutes = 498 seconds.

z = 498 * 3

z = 149400000 km

OR

z = 149.4 million km

Hope it helps!

A child at the top of a slide de has a gravitational store of 1800J. What is the child's maximum kinetic store as he slides down? Explain why

Answers

Hi there!

We know that:

Initial Total Mechanical Energy = Final Total Mechanical Energy

(Ei = Ef)

In this instance:

Ei = Gravitational Potential Energy

Ef = Kinetic Energy

In the absence of friction, ALL of the initial potential energy will be changed into kinetic energy at the bottom of the slide. Thus, the maximum kinetic energy of the child will be 1800 J.

A glass beaker of unknown mass contains of water. The system absorbs of heat and the temperature rises as a result. What is the mass of the beaker? The specific heat of glass is 0.18 cal/g ∙ °C, and that of water is 1.0 cal/g ∙ C°.

Answers

From the information provided in the question, the mass of the beaker is 144.4 g.

From the information provided in the complete question;

volume of water = 74 mL

Mass of water = 74 g

specific heat of glass = 0.18 cal/g ∙ °C

specific heat of water = 1.0 cal/g ∙ C°

Mass of glass =  x g

Total heat gained by the system = 2000.0cal

Temperature rise = 20.0°C

Heat gained by system = Heat gained  by glass + Heat gained by water

Heat gained by glass = x ×  0.18 × 20

Heat gained by water = 74  ×  1.0 × 20

Hence;

2000 =  (x ×  0.18 × 20) + ( 74  ×  1.0 × 20)

2000 - 1480 =  (x ×  0.18 × 20)

x = 520/3.6

x = 144.4 g

Missing parts;

A glass beaker of unknown mass contains 74.0 ml of water. The system absorbs 2000.0cal of heat and the temperature rises 20.0°C as a result. What is the mass of the beaker? The specific heat of glass is 0.18

cal/g °C, and that of water is 1.0 cal/g °C.​

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2.(01.01 LC)
Which of the following is true for gravitational force? (3 points)
Decreases with increase in mass
Increases with increase in mass
Increases with increase in distance
Decreases with decrease in distance

Answers

Answer:

Increases with increase in mass

Explanation:

gravity is proportional to mass and inversely proportional to the square of the distance between them

F = GMm/d²

Please help
A man stands on a freely rotating platform with his arms extended, his rotational frequency is 0.25rev/s. But when he draws them in, his frequency is 0.80revs/s. Find the ratio of his moment of inertia in the first case to that in the second.​

Answers

Answer:

sorry for you

The ratio of the man's moment of inertia in the first case (arms extended) to that in the second case (arms drawn in) is 3.2.

The relationship between the rotational frequency [tex](\(\omega\))[/tex] and moment of inertia (I) is given by the equation:

[tex]\[I_1\omega_1 = I_2\omega_2\][/tex]

where [tex]\(I_1\)[/tex]and [tex]\(I_2\)[/tex] are the moments of inertia in the two cases, and [tex]\(\omega_1\) and \(\omega_2\)[/tex] are the corresponding rotational frequencies.

Let's denote the moment of inertia in the first case (arms extended) as [tex]\(I_1\)[/tex] and in the second case (arms drawn in) as [tex]\(I_2\)[/tex]. The given rotational frequencies are [tex]\(\omega_1 = 0.25 \, \text{rev/s}\) and \(\omega_2 = 0.80 \, \text{rev/s}\)[/tex].

Using the equation [tex]\(I_1\omega_1 = I_2\omega_2\)[/tex], we can rearrange it to solve for the ratio of moments of inertia:

[tex]\[\frac{I_1}{I_2} = \frac{\omega_2}{\omega_1}\][/tex]

Substituting the given values, we have:

[tex]\[\frac{I_1}{I_2} = \frac{0.80 \, \text{rev/s}}{0.25 \, \text{rev/s}}\][/tex]

Simplifying the expression, we get:

[tex]\[\frac{I_1}{I_2} = 3.2\][/tex]

Therefore, the ratio of the man's moment of inertia in the first case (arms extended) to that in the second case (arms drawn in) is 3.2.

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20 cm long 10 cm wide and 5 cm thick as a mass of 500 g determine the greatest pressure that can be exerted by block on the flat surface?​

Answers

100000 Pascal

Explanation:

pressure= force/area

Max pressure= force/min area

so f=5

min area= 5×10^-5

5÷5*10^-5 = 100000pascal

Which is a force that wears away landforms? Select three options.

A. weathering
B. erosion
C. humans
D. clouds
E. light

Answers

The answer is A, B and C. Clouds and light do not weather landforms.

PLEASE HELP! I USED 100 POINTS!
Complete the sentence.

_____ are cracks in rock layers, and the pressures within the crust can push one of these layers past another.

A. Faults
B. Tectonic plates
C. Stalagmites

Subject: Science

Answers

Answer:

A i think its right im postivite

Answer: A. Faults

Explanation: ;-; its easy because faults are cracks and they can push layers past each other making tectonic plates rub against each other then creating a earthquake

Two ends of a steel wire of length 8m and 2mm radius are fixed to two rigid supports. Calculate the increase in tension when the temperature falls by 10°C. Given linear expansivity of steels = 12x10^_6 per kelvin and Young's modules for steel =2x10^11 n/m^2 ​

Answers

The increase in tension on the steel wire is 8,484.75 N.

The given parameters;

original length of the wire, l = 8 mradius of the wire, r = 2 mm

The area of the steel wire is calculated as follows;

[tex]A = \pi r^2\\\\A = \pi \times (2\times 10^{-3})^2\\\\A = 1.257 \times 10^{-5} \ m^2[/tex]

The extension of the steel wire is calculated as follows;

[tex]\Delta l = \alpha \times l\times \Delta T\\\\\Delta l = (12\times 10^{-6}) \times (8) \times (10 + 273)\\\\\Delta l = 0.027 \ m[/tex]

The increase in tension on the steel wire is calculated as follows;

[tex]E = \frac{stress}{strain } = \frac{\ F/A}{\Delta l/l} \\\\E = \frac{F\times l}{A \times \Delta l} \\\\F = \frac{E\times A \times \Delta l }{l} \\\\F = \frac{(2\times 10^{11}) \times (1.257\times 10^{-5})\times 0.027}{8} \\\\F = 8,484.75 \ N[/tex]

Thus, the increase in tension on the steel wire is 8,484.75 N.

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Suppose that Hubble's constant were H0 = 51 km/s/Mly (which is not its actual value). What would the approximate age of the universe be in that case?

Answers

Given the Hubble's constant, the approximate age of the universe is 5.88 × 10⁹ Years.

Given the data in the question;

Hubble's constant; [tex]H_0 = 51km/s/Mly[/tex]

Age of the universe; [tex]t = \ ?[/tex]

We know that, the reciprocal of the Hubble's constant ( [tex]H_0[/tex] ) gives an estimate of the age of the universe ( [tex]t[/tex] ). It is expressed as:

[tex]Age\ of\ Universe; t = \frac{1}{H_0}[/tex]

Now,

Hubble's constant; [tex]H_0 = 51km/s/Mly[/tex]

We know that;

[tex]1\ light\ years = 9.46*10^{15}m[/tex]

so

[tex]1\ Million\ light\ years = [9.46 * 10^{15}m] * 10^6 = 9.46 * 10^{21}m[/tex]

Therefore;

[tex]H_0 = 51\frac{km}{\frac{s}{Mly} } = 51000\frac{m}{s\ *\ Mly} \\\\H_0 = 51000\frac{m}{s\ *\ (9.46*10^{21}m)} \\\\H_0 = 5.39 *10^{-18}s^{-1}\\[/tex]

Now, we input this Hubble's constant value into our equation;

[tex]Age\ of\ Universe; t = \frac{1}{H_0}\\\\t = \frac{1}{ 5.39 *10^{-18}s^{-1}} \\\\t = 1.855 * 10^{17}s\\\\We\ convert\ to\ years\\\\t = \frac{ 1.855 * 10^{17}}{60*60*24*365}yrs \\\\t = \frac{ 1.855 * 10^{17}}{31536000}yrs\\\\t = 5.88 *10^9 years[/tex]

Therefore, given the Hubble's constant, the approximate age of the universe is 5.88 × 10⁹ Years.

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a An object is tarown up with a velocity v = 6.02 +7.0j. Calculate the (1) time taken reach the maximum height (ii) the horizontal range (s = 10m/s2). ​

Answers

Answer:

(i) 0.6s (ii) 8.42m

Explanation:

U² = 6.02² + 7²

U = 9.23

angle of projection

tanø = 6.02/7

ø = 40.7

Time of fligt

t = Usinø/g

t = 9.23 sin 40.7/10

t = 0.6

H range = U²sin2ø/g

H = 9.23²sin 81.4/10

H = 8.42m

The time taken reach the maximum height is 0.6s and the horizontal range is 8.42m.

What is Velocity?

Velocity ​​is defined as the directional motion of an object which is indicated by the rate of change of position as observed from a particular frame of reference. It is measured by a particular standard of time. It is a vector quantity as it has both magnitude and direction.

It can be expressed as:

v= d/t

Where. v is the velocity in m/s

d is the displacement measured in meter 'm'

t is the time measured in seconds 's'

For above given information,

v = 6.02 +7.0j, so the initial velocity will be u

u² = 6.02² + 7²

u = 9.23m/s

Angle of projection, tanø = 6.02/7

ø = 40.7

Time taken=  t = u sinø/g

t = 9.23 sin 40.7/10

t = 0.6s

Horizontal range  = u²sin2ø/g

H = 9.23²sin 81.4/10

H = 8.42m

Thus, the time taken reach the maximum height is 0.6s and the horizontal range is 8.42m.

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Which is NOT a function of the
cell wall?
A. Protects cell from bursting
B. Provides support for plant cells
C. Protects cell from harsh internal
environments
D. Absorbs sunlight to give energy to the cell

Answers

Answer:

The answer is D

Explanation:

The chloroplast absorbs sunlight for energy not the cell wall

D, the sunlight is absorbed in the chloroplasts

A projectile is launched with a horizontal velocity of 20 m/s and an initial vertical velocity of 20 m/s. What is the projectile's acceleration in the Horizontal direction? Verticle direction?

Answers

Answer:

Vertical acceleration 9.8 m/s² downward

Horizontal acceleration 0.0 m/s²

assuming no air resistance.

what are the greenhouse gasses in the earth that are primarily responsible for the greenhouse effect on Earth

Answers

Answer:

Water Vapour, Carbon dioxide, methane,nitrous oxide,ozone.

A 220 g mass is on a frictionless horizontal surface at the end of a spring that has force constant of 7.0
Nm-1
. The mass is displaced 5.2 cm from its equilibrium position and then released to undergo simple
harmonic motion.
At what displacement from the equilibrium position is the potential energy equal to the kinetic energy.

Answers

The conservation of energy allows to find the result for the point where the kinetic and potential energy are equal is;

       x = 0.026 m

Given parameters

The mass of the body m = 220 g = 0.220 kg The force constant k = 7.0 N / m The initial displacement or amplitude xo = 5.2 cm = 0.052 m

To find

The point where scientific and potential energy are equal.

 

The law of the conservation of mechanical energy is one of the most important in physics, stable that if there is no friction, the mechanical energy of the system is conserved. The mechanical energy is formed by the sum of the kinetic energy and the potential energies.

               Em = K + U

Let's write the energy in two points.

Starting point. With maximum compression.

        Em₀ = U = ½ k x²

Final point. Where the kinetic and potential energy are equal.

        [tex]Em_f = K +U[/tex]  

Since the mechanical energy is constant at this point K = U, therefore we can write the energy.

        [tex]Em_f = 2U = 2 ( \frac{1}{2} \ k \ x_f^2 )[/tex]

 

Energy is conserved.

        [tex]Em_o = Em_f \\\frac{1}{2} \ k x_o^2 = 2 ( \frac{1}{2} \ k x_f^2)[/tex]Emo = Emf

        ½ k x² = 2 (½ k xf²)

        [tex]x_f = \frac{x_o}{2}[/tex]  

       

let's calculate.

        [tex]x_f = \frac{0.052}{2} \\x_f = 0.026 m[/tex]  

In conclusion using the conservation of energy we can find the point where the kinetic and potential energy are equal is;

       x = 0.026 m

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A 500 kg cart is rolling to the right at 1.3 m/s. a 60 kg man is standing on the right end of the cart. what is the speed of the cart if tha man suddenly starts running to the left with a speed 10.0 m/s relative to the cart

Answers

Answer:

P1 = 1.3 (500 + 60) = 728 kg-m      total momentum to right at start

P2 = (v2 - 10) 60 + 500 v2

total momentum after running at -10 with respect to cart = 728 where v2 is the new speed of the cart

728 = 560 v2 - 600

v2 = 1328 / 560 = 2.37 m/s    new speed of cart

Check:

After:    p2 for cart = 500 * 2.37 = 1186

p1 for man = (2.37 - 10) * 60 = -458

P2 = p1 + p2 = 728       total momentum unchanged

As a bicycle pump inflates a tyre, it pressure rises from 30 kPa to 40 kPa at constant temperature of 30 °C. By assuming the air acts as an ideal gas, calculate the work done per mol of the air.
A. -80.35 J
B. 80.35 J
C. -811.93 J
D. 811.93 J

(please show calculation)
can use this formula W=nRT ln(p1/p2)​

Answers

Answer:

B.-80.35 J

i dont know the calculation

Which light is most sensitive to the eyes?

Answers

Answer:

Our eyes are most sensitive to the wavelengths corresponding to the yellow and green colors of the spectrum. Flashy signs and some fire engines are painted in a yellowish-green color to attract our attention.

Calculate the amount of work done (in joules) to raise the 0.2kg mass 0.5 m

Answers

Answer:

1

Explanation:

A=mgh=0.2*10*0.5=1 J

A patient comes to an outpatient laboratory for a physician-ordered fasting test. The patient indicates that he forgot that the test was to be fasting and ate a candy bar 2 hours ago. The patient insists that you should draw the test because he cannot come back at another time. What should you do?

Answers

The patient eating a candy bar instead of fasting for the test should be told

that the test results will be wrong and he may receive a wrong diagnosis.

The medical practitioners told him to fast when coming for a reason and he

forgetting and eating something means the objective for the test may have

been defeated.

This is why it's best to explain to him about the consequences of his actions

which is likely getting a wrong result and diagnosis.

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What's the kinetic energy of an object that has a mass of 12 kilograms and moves with a velocity of 10 m/s?

Answers

Answer:

600 J

Explanation:

Given,

Mass (m) = 12 kgVelocity (v) = 10 m/s

As we know,

Kinetic Energy,

[tex] E_{k} \: = \frac{1}{2} m {v}^{2} [/tex]

Therefore ,

Kinetic energy of the object is,

[tex] = \frac{1}{2} \times 12 \: kg \times 10 \: m {s}^{ - 1} \times 10 \: m {s}^{ - 1} [/tex]

(On dividing 12 by 2 we get 6)

= (6 × 10 × 10) J [As 'J' stands for 'joule']

= 600 J (Ans)


An object weighs 573.0 N on planet Xyleneer. If the object's mass is 92.1 kg, what is the acceleration due to gravity on planet Xyleneer?

Answers

Answer:

a = 6.22 m//s²

Explanation:

F = ma

a = F/m

a = 573.0 / 92.1

a = 6.221498...

Answer:

[tex]\boxed {\boxed {\sf 6.22 \ m/s^2}}[/tex]

Explanation:

We are asked to find the acceleration due to gravity on another planet.

Weight is the measure of the force of gravity. Therefore, we can use the following version of the force formula:

[tex]F_g=mg[/tex]

In this formula, [tex]F_g[/tex] is the weight, m is the mass, and g is the acceleration due to gravity.

The object weights 573.0 Newtons (or 573.0 kg*m/s²) on the planet. The object has a mass of 92.1 kilograms.

[tex]F_g[/tex]= 573.0 kg* m/s²m= 92.1 kg

Substitute these values into the formula.

[tex]573.0 \ kg*m/s^2 = 92.1 \ kg * g[/tex]

We are solving for g, so we must isolate the variable. It is being multiplied by 92.1 kilograms. The inverse of multiplication is division, so divide both sides of the equation by 92.1 kg.

[tex]\frac {573.0 \ kg*m/s^2}{92.1 \ kg}= \frac{92.1 \ kg*a}{92.1 \ kg}[/tex]

[tex]\frac {573.0 \ kg*m/s^2}{92.1 \ kg}=a[/tex]

The units of kilograms cancel.

[tex]6.22149837 \ m/s^2=a[/tex]

The original measurements of weight and mass have 4 and 3 significant figures. Our answer must have the least number of sig figs, or 3. For the number we found, that is the hundredth place. The 1 in the thousandths place tells us to leave the 2 in the hundredth place.

[tex]6.22 \ m/s^2=a[/tex]

The acceleration due ot gravity on planet Xyleneer is approximately 6.22 meters per second squared.

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