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3 years ago

What causes the apparent motions of stars across the sky each night

Physics

1 answer:

densk [106]3 years ago

3 0

Answer:

Explanation:

for the motion every night, it is because the Earth spins on its axis.

for the changes over a year, this is because the Earth rotates around the sun.

for the changes over hundreds, thousands or millions of years, this is because the whole solar system (including the Earth, of course) rotates with all the other stars in our galaxy around the center of the galaxy. and each star system has its own orbit (similar to the planets in our solar system).

it is very rare to see objects outside of our galaxy without a telescope, but they change too over a long period of time, because our galaxy not only rotates by also moves through the universe, and these other objects move on their own too.

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Electromagnetic induction

vredina [299]

Answer:

Electromagnetic Induction or Induction is a process in which a conductor is put in a particular position and magnetic field keeps varying or magnetic field is stationary and a conductor is moving. This produces a Voltage or EMF (Electromotive Force) across the electrical conductor.

3 0

3 years ago

Read 2 more answers

1. The resistance of an electric device is 40,000 microhms. Convert that measurement to ohms.

lidiya [134]

Answer:

The answer would be 0.04ohms.

Explanation:

Hopefully this helps

4 0

3 years ago

Read 2 more answers

A bullet with a mass 2.25g is fired up into the air with a velocity of 187.5 m/s. What is the maximum height of the bullet

Ksivusya [100]

Answer:

1793.7m

Explanation:

From the principle of conservation of energy; the kinetic energy substended by the object equals the potential energy sustain by the object when it gets to its maximum position.

Now the kinetic energy; is

K.E = 1/2 × m × v2

Where m is mass

v is velocity

Hence.

K.E = 1/2 × 2.25 × (187.5)^2

Now this should be same with the potential energy which is given as;

P.E = m× g× h

Where m is mass of object

g is acceleration of free fall due to gravity = 9.8m/S2

h is maximum height substain by the object.

Hence P.E = 2.25 × 9.8 × h

From the foregoing analysis of energy conversation it implies;

1/2 × 2.25 × (187.5)^2 =2.25 × 9.8 × h

=> 1/2 × (187.5)^2 = 9.8 × h

=>1/2 × (187.5)^2 / 9.8 = h

=> 1793.69m = h

h= 1793.69m

h =1793.7m to 1 decimal place

3 0

3 years ago

I just need a full answer here not only so I can answer the question, but also so that I can learn.

Xelga [282]

Answer: Number of valence electrons determine how fast or easy for an atom to gain stability. Either by gaining electrons or by losing electrons.

Group one and seven elements react fast because they only have one electron to gain or lose.

Explanation:

Number of valence electrons tell us the number of electrons an atom will gain or lose in order to attain stability in electron configuration.

All the elements in a particular group will have the same number of valence electrons as follows:

Group one - 1 valence electron

Group two - 2 valence electrons

Group three - 3 valence electrons

Group four - 4 valence electrons

Group five - 3 valence electrons

Group six - 2 valence electrons

Group seven - 1 valence electron

Group eight - 0 valence electron

Some elements are more reactive than the others because of the electron affinity, oxidation state and electronegativity of the atoms

For instance, elements in group 7 are more reactive than others because of their oxidation state and they have very high electronegativity.

Also, group one elements are more reactive because they only have one electron to loose.

7 0

3 years ago

Calculate, for the judge, how fast you were going in miles per hour when you ran the red light because it appeared Doppler-shift

sammy [17]

Answer:

The doppler effect equation is:

$f' = \frac{v +v0}{v - vs}*f$

In the equation we have frequencies, but then we have the wavelengths of the lights, remember the relation:

v = f*λ

then:

f = v/λ

and v is the speed of light, then:

f = c/λ

where:

f' is the observed frequency, in this case, is equal to f = (3*10^17nm/s)/550 nm

f is the real frequency, in this case, is (3*10^17nm/s)/650 nm

vs is the speed of the source, in this case, the source is not moving, then vs = 0 m/s.

v is the speed of the wave, in this case, is equal to the speed of light, v = 3*10^8 m/s

v0 is your speed, this is what we want to find.

Replacing those quantities in the equation, we get:

(3*10^17nm/s)/550 = (3*10^8 m/s + v0)/(3*10^8 m/s)*(3*10^17nm/s)/650 nm

(650nm)/(550nm) = (3*10^8 m/s + v0)/(3*10^8 m/s)

1.182*(3*10^8 m/s) = (3*10^8 m/s + v0)

1.182*(3*10^8 m/s) - (3*10^8 m/s) = v0 = 54,600,000 m/s

So your speed was 54,600,000 m/s, which is a lot.

6 0

3 years ago