How much heat does 25 g of aluminum lose when cooled from 100 ° C to 20 ° C? Express your result in BTU

Answer:

Lens of the human Eye is a important and one of that most complex sense organ.

Explanation:

Lens of the human eye it helps that in visualizing light and color perception and objects , glance on the human eye structure and function.

Sense organs are much pretty similar to the camera they  help us see the objects clear.

A human eye is the 2.3 cm in diameter and all filled some fluid, and there are following parts in eye:-  cornea,  Retina , Lens ,Pupil , optic nerves.

cornea :- the cornea is the first transparent part of is called cornea, enters the light through the cornea.

Retina :-it is light sensitive layer that consists of nerve cells,then transmitted to the brain through nerves.

Lens:- behind the pupil there is a transparent structure called lens,it shape focus light on the retina.

Pupil:-it control the value of light that enters the human eye.

Optic nerves is are the two types :- (1) cones (2) Rods .

Answer:

It causes Light Rays to converge on the retina

Explanation:

I took the K12 Test

Answer:

[tex]\lambda[/tex] = 40 cm

Explanation:

given data

string length = 30 cm

solution

we take here equation of length that is

L = [tex]n \times \frac{1}{4} \lambda[/tex]     ...............1

so

total length will be here

[tex]L = \frac{\lambda}{2} + \frac{\lambda}{4}\\[/tex]

[tex]L = \frac{3 \lambda }{4}[/tex]

so [tex]\lambda[/tex]  will be

[tex]\lambda = \frac{4L}{3}\\\lambda = \frac{4\times 30}{3}[/tex]

[tex]\lambda[/tex] = 40 cm

Answer:

(I). The Schwarzschild radius is [tex]2.94\times10^{8}\ km[/tex]

(II). The Schwarzschild radius is 17.7 km.

(III). The Schwarzschild radius is [tex]1.1\times10^{-7}\ km[/tex]

(IV). The Schwarzschild radius is [tex]7.4\times10^{-29}\ km[/tex]

Explanation:

Given that,

Mass of black hole [tex]m= 1\times10^{8} M_{sun}[/tex]

(I). We need to calculate the Schwarzschild radius

Using formula of radius

[tex]R_{g}=\dfrac{2MG}{c^2}[/tex]

Where, G = gravitational constant

M = mass

c = speed of light

Put the value into the formula

[tex]R_{g}=\dfrac{2\times6.67\times10^{-11}\times1\times10^{8}\times1.989\times10^{30}}{(3\times10^{8})^2}[/tex]

[tex]R_{g}=2.94\times10^{8}\ km[/tex]

(II). Mass of block hole [tex]m= 6 M_{sun}[/tex]

We need to calculate the Schwarzschild radius

Using formula of radius

[tex]R_{g}=\dfrac{2MG}{c^2}[/tex]

Put the value into the formula

[tex]R_{g}=\dfrac{2\times6.67\times10^{-11}\times6\times1.989\times10^{30}}{(3\times10^{8})^2}[/tex]

[tex]R_{g}=17.7\ km[/tex]

(III). Mass of block hole m= mass of moon

We need to calculate the Schwarzschild radius

Using formula of radius

[tex]R_{g}=\dfrac{2MG}{c^2}[/tex]

Put the value into the formula

[tex]R_{g}=\dfrac{2\times6.67\times10^{-11}\times7.35\times10^{22}}{(3\times10^{8})^2}[/tex]

[tex]R_{g}=1.1\times10^{-7}\ km[/tex]

(IV). Mass = 50 kg

We need to calculate the Schwarzschild radius

Using formula of radius

[tex]R_{g}=\dfrac{2MG}{c^2}[/tex]

Put the value into the formula

[tex]R_{g}=\dfrac{2\times6.67\times10^{-11}\times50}{(3\times10^{8})^2}[/tex]

[tex]R_{g}=7.4\times10^{-29}\ km[/tex]

Hence, (I). The Schwarzschild radius is [tex]2.94\times10^{8}\ km[/tex]

(II). The Schwarzschild radius is 17.7 km.

(III). The Schwarzschild radius is [tex]1.1\times10^{-7}\ km[/tex]

(IV). The Schwarzschild radius is [tex]7.4\times10^{-29}\ km[/tex]

The energy conservation allows to find the Schwarschild radius for several bodies of different masses are:

  1)  Black hole quasar is:  r = 2.9 10⁸ km

  2) Blsck hole supernove is:  r = 17.7 km

  3)  Mini black hole is:   r = 1.1 10⁻⁷ km

  4) Human body is:  r=  7 10⁻²⁹ km

The schwarschild radius is defined as the distance from a black hole center at radius  which the escape velocity is equal to the light speed, in some cases it is also called the event horizon.

Let's use Newton's second law where force is the universal law of attraction and acceleration is centripetal.

        F = ma

        F = [tex]G \frac{Mm}{r^2}[/tex]        

Where F is the force, M the mass of the black hole, m the handle of the body, r the radius and v the speed of the body.

The energy of the gravitational field is

        F = [tex]- \frac{dU}{dr }[/tex]  

         U = [tex]-G \frac{Mm}{r}[/tex]  

Let's use conservation of energy

        Em₀ = K + U = ½ m v² -  [tex]G \frac{Mm}{r}[/tex]  

In infinity the energy

        Em_f = 0

energy is conserved

       Em₀ = Em_f  

       ½ m v² - [tex]G \frac{Mm }{r}[/tex]  = 0

       r = [tex]\frac{2GM}{v^2}[/tex]

From the definition of the Schwarschild radius this speed is equal to the light speed

        v = c

        r = [tex]\frac{2GM}{c^2 }[/tex]  

They ask to calculate the radius for several cases of different mass, claculate the constant value

      V = [tex]\frac{2 \ 6.67 \ 10^{-11} }{(3 \ 10^8) ^2 }[/tex]  

      V =  1.482 10⁻²⁷

1) A black hole of mass M = 1 10⁸ [tex]M_{sum}[/tex]

The tabulated mass of the sun is [tex]M_{sum}[/tex] = 1.989 10³⁰ kg

Let's  substitute

        r =  1.482 10⁻²⁷   1 10⁸ 1.989 10³⁰

        r = 2.94 10⁸ km

With two significant figures

        r = 2.9 10⁸ km

2) A black hole of mass M = 6 [tex]M_{sum}[/tex]

        r =  1.482 10⁻²⁷ 6 1.989 10-30

        r = 17.7 km

3) a mini black hole with the mass of the moon

    Tabulated mass of the moon M = 7.35 10²² kg

       r =  1.482 10⁻²⁷  7.35 10²²    

       r = 1.1 10⁻⁷ km

4) A person of M = 50 kg

    r =  1.482 10⁻²⁷ 50

    r=  7 10-29 km

In conclusion using the conservation of energy we can find the Schwarschild radius for several bodies of different masses are:

  1)  Black hole quasar is:  r = 2.9 10⁸ km

  2) Blsck hole supernove is:  r = 17.7 km

  3)  Mini black hole is:   r = 1.1 10⁻⁷ km

  4) Human body is:  r=  7 10⁻²⁹ km

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Answer:

Explanation:

i )

When it is disconnected with the battery , the charge stored in it becomes fixed . When the plate distance becomes half , its capacitance becomes twice from C to 2C . Let charge stored in it at the time of disconnection from battery be Q . Let plate separation reduces from d to d / 2

So charged stored in it will remain unchanged .

ii )

Potential difference = charge / capacitance

in the first case potential difference = Q / C

in the second case potential difference = Q / 2C

So potential difference becomes half .

iii ) electric field = potential diff / plate separation

in the first case electric field = Q / (d x C )

in the second case electric field = 2 Q / (d x 2C)

= Q / (d  x C )

So electric field remains unchanged .

iv)

energy stored in first case = Q² / 2C

In the second case energy stored = Q² / 2x2C

so energy stored becomes half .

Answer:

Fuel + O2 → CO2 + H2O

Explanation:

Answer:

60

Explanation:

According to the given question, the computation of minimum coating thickness is shown below:-

The condition for constructive interference is

[tex]2t_{min} = (m + \frac{1}{2} )\times \frac{\lambda}{^nmateral}[/tex]

[tex]= (0 + \frac{1}{2} )\times \frac{\lambda}{^nmateral}[/tex]

[tex]t = \frac{\lambda}{4n}[/tex]

Now we will put the values to the above formula to reach the answer

[tex]= \frac{480nm}{4\times 2.0}[/tex]

= 60

Therefore we simply applied the above formula to determine the minimum coating thickness

The minimum coating thickness needed to ensure that light of wavelength 480 nm and of perpendicular incidence will be reflected from the two surfaces of the coating with fully constructive interference is 60.

Given that, the index of refraction of glass is 1.50 and the index of refraction of silicon monoxide is 2.00. The wavelength light of 480 nm.

If [tex]\lambda {c}[/tex] is the wavelength in the coating and λ is the wavelength in vacuum, then  [tex]\lambda_{c} = \dfrac {\lambda}{n}[/tex]  where n is the index of refraction of the coating.

Thus, the minimum coating thickness [tex]T_{min}[/tex] can be calculated as,

[tex]2T_{min} = (m+\dfrac {1}{2})\times\dfrac {\lambda} {n}\\\\T_{min} = (m+\dfrac {1}{2}) \times\dfrac {\lambda} {2n}[/tex].

For the constructive interference, m = 0.

So [tex]T_{min} = \dfrac {\lambda} {4n}[/tex]

[tex]T_{min} = \dfrac {480\rm nm} {4\times2.0}[/tex]

[tex]T_{min} = 60[/tex]

The minimum coating thickness needed to ensure that light of wavelength 480 nm and of perpendicular incidence will be reflected from the two surfaces of the coating with fully constructive interference is 60.

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https://brainly.com/question/15541641.

Answer: The keywords to input into the blank spaces were omitted which are ; fragments, increases, decreases, opaque, raises, molecular, protostar, gravitational, thermal.

Please find the answers for the blank spaces in the explanation column

Explanation:

1. The first stage of stellar formation is the assembly (or formation) of a_PROTOSTAR______ . 2. Stars form in MOLECULAR clouds. 3. When a cloud collapses, it FRAGMENTS into smaller and smaller pieces till those pieces reach stellar masses. 4. As the density increases, the fragments become_OPAQUE______ , which___RAISES_____ the temperature of the cloud and inhibits further fragmentation. 5. The __FRAGMENTS_____then condense into rotating globs of gas that serve as stellar embryos. 6. During this stage the surface temperature INCREASES_______ and luminosity__INCREASES_______ despite decreasing size. 7. The central temperature and pressure increase as the GRAVITATIONAL potential energy is converted to energy due to THERMAL contraction.

The above describes the evolution or formation of stars which begins with the collapse of a molecular cloud by gravitational force, this collapse cause the molecular cloud to fragment with the release of heat --Gravitation potential energy causing an increased temperature and pressure of the newly condensing  fragment with increasing luminosity known as a Protostar.

Answer:

Velocity

Explanation:

You would be describing the velocity of the car.

Velocity in physics is defined as Vector quantity that describes the displacement of an object with respect to the time it takes to attain it. Displacement is the addition of direction to the speed of an object. The displacement is noted in the question, "traveling eastward". While it is stated that the car travels at 44.704 m/s. Ordinarily, it would have been tagged speed, if not for the direction added to it which makes it velocity.

I hope you understand.

Answer:

d = 343 m

Explanation:

Given that,

You notice that an echo took 2 seconds before you heard the echo of your yell.

We need to find that how far away is the canyon wall that reflected your yell. It means we need to find the distance.

The distance covered by an object is given by :

d = v × t

v is speed of sound in air, v = 343 m/s

The sound took 1 s to reach the wall and 1 s back to you.

It means that,

d = 343 × 1

d = 343 m

So, canyon will reflect your yell at a distance of 343 m

Answer:

drug misuse

Explanation:

this is because the person is using those drugs but indiscriminately meaning without correct judgement or in this context without a prescription therefore without following guidelines and legal standards eg self medication

but it is not abuse because it is being used for its intended purpose just without any guidelines

Answer:

When we have irregular objects, it may become very hard to calculate the volume of the object, as we actually can not use any simple equation to find it.

The mass is less tricky, just find a scale and wheight it, now we know the mass of the irregular object.

One way to measure the volume of the object is using water... how we do it?

Get some recipient with water, measure the height of the water.

Introduce your object into the water and totally submerge it, now the level of the water will rise. This is because as you introduce the object under the water, you are displacing up a given volume of water that has the same volume as the irregular object.

Now that you know the height of the water before and after you put your object, you can easily calculate the volume of water displaced, and that will be the volume of the object (the tricky part may be totally submerging the object if, for example, is wood and it floats, here you can use a thin wire to push it down but it will affect a little bit the measures.)

Answer:

kinetic energy will be equal to 0

Explanation:

this is because at final position velocity of body will become zero.

kinetic energy eill be 8 times

Answer:

40 ms¯².

Explanation:

To solve this problem, we shall illustrate the question with a diagram.

The attached photo gives a better understanding of the question.

From the attached photo:

Velocity (v) = 160 ms¯¹

Time (t) = 4 secs.

Acceleration (a) =?

Acceleration (a) = Velocity (v) /time (t)

a = v/t

a = 160/4

a = 40 ms¯²

Therefore, the initial acceleration of the rocket is 40 ms¯².

Answer:

66.7 cm

Explanation:

The focal length is half the radius of curvature, or f = 40 cm.

The image is real, so i = +100 cm.

The distance to the object is therefore:

1/o + 1/f = 1/i

1/o + 1/40 = 1/100

o = -66.7 cm

The object is 66.7 cm left of the mirror.

Answer:

Inference

Explanation:

An inference involves the application of logic to progress from a premise to a conclusion or logical consequence on the basis of the evidence or known fact. Inference is a process of thought that be divided into a deduction and an induction aspect.

In the given question Halley, by standing outside was able to deduce the sound of thunder she is then able by inductive reasoning from the fact that storms are usually preceded by and accompany lightening, conclude that there is a storm coming.

Answer:

The output force would decrease since exerted force is inversely proportional to contact area.

Explanation:

F ∝ [tex]\frac{1}{A}[/tex] , Where 'F' is the exerted force and 'A' is the contact area.

Answer:

Explanation:

a) From the diagram, the load will be expressed in newton. The load will be the weight of the box on the inclined plane.

Load = mass * acceleration due to gravity.

Given the mass of the object = 100kg

acceleration due to gravity = 9.8m/s²

Load (in Newton) = 100*9.8

Load (in Newton) = 980N

b) The formula for calculating the velocity ratio of an inclined plane is expressed as VR = 1/sinθ where θ is the angle of inclination.

Given θ = 30°,

VR = 1/sin30°

VR = 1/0.5

VR = 1/(1/2)

VR = 1* 2/1

VR = 2

The velocity ratio is 2.

c) Length of the inclined plane can be calculated using the SOH, CAH, TOA trigonometry identity.

According to SOH, sinθ = opposite/hypotenuse

sin30°  = 1/2 = opp/hyp

This shows that the opposite side of the triangle is 1 and the hypotenuse is 2. The length if the inclined is the length of the longest side i.e the hypotenuse. Hence the length of the inclined plane is 2m

d) Mechanical Advantage is the ratio of the load to the effort applied on an object.

Given the Load = 980N and the effort applied to the load on the incline plane = 400N

MA = Load/Effort

MA = 980/400

MA = 2.45

e) Efficiency = MA/VR * 100

Efficiency = 2.45/2 * 100

Efficiency  = 122.5%

Answer:

It took the car 3 second to come to full stop

Explanation:

When the car is driving to the right at a speed of 2 m/s, and suddenly brakes giving the car a constant negative acceleration making it travel 3 meters after it stops, we can use the following kinematic equation to solve for the acceleration applied by the brakes:

[tex]v=v_0-a\,t\\0=2-a\,t\\a=\frac{2}{t}[/tex]

and we use this result in the following kinematic equation for the distance traveled to find the time it took it to stop:

[tex]x-x_0=v_0\,t-\frac{1}{2} a\,\,t^2\\3=2\,t -\frac{1}{2} (\frac{2}{t}) \,\,t^2\\3=2\,t-t\\3=t[/tex]

therefore, it took the car 3 seconds to come to a full stop.

Answer:

(a) The convex mirror image, is always upright at all positions, while images formed by concave mirrors are always inverted when the object distance from the mirror is more than the mirrors focal length.

(b) An upright image is not seen for object at a distance from a concave mirror further than the focal length of the mirror, which is the spoon in the question

Therefore, the location of her eyes of approximately, 30 cm,  from the mirror is more than the mirror's focal length

Explanation:

Explanation:

The asked in the Question is missing, although i am assuming the number

as [tex]\frac{6}{23}[/tex] ÷[tex]\frac{\sqrt{2} }{2}[/tex].

The given expression contains an irrational number. So, the quotient will also be an irrational number.

Solving

[tex]\frac{6}{23}\times\frac{\sqrt{2} }{2} \\=\frac{3\sqrt{2} }{23}[/tex]

Which is an irrational number.

Answer:

The atom is mostly empty space.

Explanation:

Ernest Rutherford in the year 1911 developed a model of an atom. In his model the atom was shown that the atom is mostly empty spaces composed of negative electrons which orbits round a positive nucleus just like planets revolving round the sun.

Rutherford came up with this model by performing experiments in 1909 which involves the scattering of alpha particles on a thin gold foil. From this experiments he came up with his model.

Answer:

A!

Explanation:

The atom is mostly empty space.

Answer:

Explanation:

The weight of a body is defined as the force with which it is attracted towards the centre of a planet. A spring balance measures it. It's unit is Newton ( N ) in the SI system and dyne in the CGS system.

Hope I helped!

Best regards!

Weight is force.

The CGS unit of force is the dyne.

The SI unit of force is the Newton.

Answer:

20 m

Explanation:

The ball travels 4 m up, then 16 m down.  It travels a total distance of 20 m.

Answer:

The longer the wave, the deeper the wave base - True

The greater the wave height, the deeper the wave base - false

The longer the wave, the faster the wave travels- true

The greater the wave height, the faster the wave travels- false

The faster the wave, the greater the wave height - False

Explanation:

When a wave has a high length it means that the wave base will be deeper.

The longer the wave, the deeper the wave base - True

When the weight height is big , the wave base will be deeper.

The greater the wave height, the deeper the wave base - false

The longer the wave, the faster the wave travels- true

The greater the wave height, the faster the wave travels- false

The faster the wave, the greater the wave height - False

Explanation:

2. Sum the torques about the fulcrum.

(450 N) (2 m) − (350 N) x = 0

x = 2.57 m

3. Sum the torques about the fulcrum.

(3600 N) (0.20 m) − F (0.90 m) = 0

F = 800 N

Mechanical advantage is the ratio between the load force and effort force.

MA = 3600 N / 800 N

MA = 4.5

Velocity ratio is the mechanical advantage divided by efficiency.  Assuming the lever is 100% efficient:

VR = 4.5 / 1

VR = 4.5

4. Mechanical advantage is the ratio between the load force and effort force.

MA = 900 N / 600 N

MA = 1.5

The velocity ratio is the distance moved by the effort divided by the distance moved by the load.  For a 3 pulley system, VR = 3.

Efficiency is mechanical advantage divided by velocity ratio.

e = 1.5 / 3

e = 0.50

5. Sum the torques about the fulcrum.

(-300 N) (0.10 m) + F (0.03 m) = 0

F = 1000 N

Answer:

940 nanometers wavelength, and about an 300 mHz - 400 gHz frequency

Answer:

Explanation:

We shall represent the point of destination and point of new starting point in vector form .

i and j will represent east and north .

point of destination = 123 j

starting point = 112 i

distance between the two

D = 123 j - 112 i

magnitude of D = √ ( 123² + 112² )

= 166.35 km

Direction of D

Tanθ = -  123 / 112

= - 1.09

θ = 132.54 degree from east in positive angle .

Answer:

First, as you may know, the light travels at a given velocity.

In vaccum, this velocity is c = 3x10^8 m/s.

And we know that:

distance = velocity*time

Now, if some object (like a star ) is really far away, the light that comes from that star may take years to reach the Earth.

This means that the images that the astronomers see today, actually happened years and years ago (So the night sky is like a picture of the "past" of the universe)

Also, for example, if an astronomer sees some particular thing, he can apply a model (a "simplification" of some phenomena that is used to simplify it an explain it) and with the model, the scientist can infer the information of the given thing some time before it was seen.

The astronomers could know what was happening inside galaxies way back then by the fact that;

they examine the spectra of galaxies (or the overall colors of galaxies) with the highest redshifts they can find

Astronomers Measure the wavelength of the light that is stretched, so the light is seen as 'shifted' towards the red part of the spectrum by using spectroscopy. This measure is also called redshift.

This invokes a ray of light through a triangular prism that splits the light into various components known as spectrum.

The way the astronomers could use this concept to know what was happening in the galaxies before is by examining the spectra of galaxies that have the highest redshifts.

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Answer:

the partial pressure of nitrogen after the air has been heated is 2.61atm

Explanation:

Using combined gas law which is the combination of Boyle's Law and Charles' Law, and it gives The relationship between pressure, volume, and absolute temperature

PV/T= K

P1₁V₁/T₁=P₂V2₂/T₂

P₂=final pressure= ?

P₁= initial pressure=2.45 atm

.T₁= initial temperature= 273k

T₂= final temperature= 550 K,

We can make P₂ subject of the formula then we have

P₂=P₁V₁T₂/T₁T₂

=( 2.45×8×550)/(273×11.8)

P2=3.35atm

Now we can calculate the partial pressure of N₂

N₂= 3.35×(78.08/10)

=2.61atm

Therefore, the partial pressure of nitrogen after the air has been heated is 2.61atm