1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Helen [10]
3 years ago
9

explain why for thousands of years people believed that stars moved across Earth's sky. Explain why we now have a different expl

anation of why stars move across the night sky. Be sure to mention reference points.
Physics
1 answer:
Anarel [89]3 years ago
6 0

Answer:

Ptolemy proposed a model, he reference system is centered on the Earth

Copernicus, proposed a deferent system,  this system is centered on the Sun, where it is at the origin of the system

Explanation:

Thousands of years ago, Ptolemy proposed a model to explain the movement of the planets and stars in the sky, in this model the reference system is centered on the Earth, so each body is orbiting in different spheres around the Earth as its center, this system had very complicated calculations and curves to be able to explain the orbits of the planets.

More recently Copernicus, proposed a deferent system, this system is centered on the Sun, where it is at the origin of the system, in this system the movement of the planets are ellipses, which is a much simpler explanation and has been widely accepted, in current systems the reference system is fixed in the bodies more massive, since this simplifies the explanation of the movements.

You might be interested in
Two charges that are separated by one meter exert 1-n forces on each other. if the magnitude of each charge is doubled, the forc
Goshia [24]
The electrostatic force between the two charges is
F=k_E  \frac{q_1 q_2}{r^2}
where q1 and q2 are the magnitudes of the two charges, and r the distance between them.

We can see from the formula that F is proportional to the product between the two charges:
F \sim q_1 q_2
so, if the magnitude of each charge is doubled, the new force will get a factor 4:
F' \sim (2 q_1 )(2 q_2 )=4 q_1 q_2 =4 F
So, the new force will be 4 times the original force:
F' = 4 \cdot 1N= 4N
5 0
3 years ago
When advertisers use well known, attractive people to sell their products, the attractive people are being used as a
Bond [772]
I dont know like a commercial seller person
6 0
2 years ago
A sound wave in air has a frequency of 354 Hz and travels with a speed of 343 m/s. How far apart are the wave crests in meters.
dsp73

Given :

The frequency of travelling sound = f = 282 Hz

The speed of travelling sound = c = 343 m/s

To Find :

The distance of waves crests

Solution :

∵ wavelength of sound wave =

i.e         =

Or,        =

∴          = 1.12   m

So, The wavelength of sound wave =   = 1.21  m

Thus , The distance of waves crests =wavelength of sound wave = 1.21 m

Hence, The distance of waves crests is 1.21 meters    Answer

6 0
2 years ago
A football kicked off at an angle 20° from the ground reaches a maximum height of 4.7 m. What is the initial velocity of the kic
Svetradugi [14.3K]
The motion of the football that is being kicked follows a projectile path and is parabolic in shape. It has a maximum height  of meters and the angle with respect to the ground is  degrees. The maximum height is the highest position vertically that the ball could reach. From the equations of an object in a projectile motion, we use the equation <span>(V*sin20)^2 = 2gh  in order to solve for velocity, V. We do as follows:

</span><span>((V) (sin(20)))^2 = 2gh  
(V^2) (0.342^2) = 92.12 
V = √ (92.12 / 0.342^2)
V = 28.06 m/s

</span>The initial velocity of the kick would be 28.06 m/s.
6 0
3 years ago
A circular swimming pool has a diameter of 8 meters. The sides are 3 meters high and the depth of the water is 1.5 meters. How m
svetlana [45]

Answer:

Work done = 2218.97 kJ

Explanation:

Work = Force x Displacement.

Force = Weight of water.

Weight of water = Mass of water x Acceleration due to gravity.

Mass of water = Volume of water x Density of water.

Volume of water = Base area of swimming pool x Depth of water.

Base area of swimming pool

= \frac{\pi  {d}^{2} }{4}  = \frac{\pi  \times \:  {8}^{2} }{4} = 50.27 {m}^{2}

Depth of water = 1.5 m

Volume of water

= 50.27 \times1.5 = 75.40 {m}^{2}

Mass of water = 75.40 x 1000 = 75400 kg

Weight of water = 75400 x 9.81 = 739656 N

Work done = 739656 x 3 = 2218.97 kJ

4 0
2 years ago
Other questions:
  • What did B.F. skinnier believe drove ones behaviors
    7·1 answer
  • A force of 49N causes a box to move with an acceleration of 7m/s2. Find the mass of the object
    9·1 answer
  • A 1.35 V potential difference is maintained across a 1.1 m length of tungsten wire that has a cross-sectional area of 0.72 mm2 .
    6·1 answer
  • The attractive electrostatic force between the point charges +8.46 ✕ 10-6 and q has a magnitude of 0.967 n when the separation b
    5·1 answer
  • For a certain optical medium the speed of light varies from a low value of 1.90 × 10 8 m/s for violet light to a high value of 2
    12·1 answer
  • Consider a 100 g object dropped from a height of 1 m. Assuming no air friction (drag), when will the object hit the ground and a
    13·1 answer
  • Elements have the same number of ______ as you move from left to right
    15·2 answers
  • An open organ pipe of length 0.47328 m and another pipe closed at one end of length 0.702821 m are sounded together. What beat f
    7·1 answer
  • John recently suffered a blow to his head. Since then, he finds it difficult to comprehend what others say to him. He also finds
    12·1 answer
  • Sentence A: At the same time, teachers will benefit from teaching fewer students per semester and gaining more one-on-one time w
    9·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!