Suppose Eratosthenes’ results for Earth’s circumference were quite accurate. If the diameter of Earth is 12,740 km, what is the length of his stadium in kilometers?
Answer:
Length of one stadium = 0.1556 km
Explanation:
We have the diameter of Earth = 12740 km
Thus, circumference (C) of Earth is
[tex]=2\pi \frac{Diameter}{2} \\[/tex]
[tex]=2\times \pi \times \frac{12740}{2}[/tex]
C = 40023.89 km
Eratosthenes was a Greek polymath. He was the first to calculate the circumference of Earth. He had observed that at local noon on day of Summer Solstice, when Sun is overhead for the locations on Tropic of Cancer, a place named Syene had zero shadow day. Also on the same day the objects in Alexandria casts shadow. This proved that Earth is spherical and not flat. He went further and calculated the Sun angle ([tex]\theta[/tex]) for Alexandria by using a Rod (Gnomon). He found the angle to be about 7°. He also knew the distance (D) between Alexandria and Syene which was 5000 Stadia.
Lets say length of one stadia = S km
He used this data and simple concept of geometry as given below:
[tex]\frac{\theta }{360}=\frac{D}{C}[/tex]
[tex]=\frac{7}{360}=\frac{5000 \times S}{40023.89}[/tex]
[tex]=5000 \times S = \frac{7\times 40023.89}{360}[/tex]
[tex]=S = \frac{7\times 40023.89}{360\times5000}[/tex]
S = 0.1556 km
give an example of fluid friction
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Describe an environment in which the sound of a ringing cell phone could not be transmitted, and explain why the ringing wouldn't be heard. Justify your reasoning using complete sentences.
Answer:
Explanation:
The sound of a ringing cellphone could not be transmitted or heard if the cellphone is enclosed in some sort of closed container from which the air has been removed. Sound is a mechanical wave, and so it must have some material substanceto travel through. Otherwise sound cannot travel from one place to another. The sound of the ringing could not travel through the vacuum inside the container if all the air were removed.
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1. What is the force on an object due to its mass and gravity called?
A)Kilograms
B)Velocity
C)Weight
D)Pounds
2. Which of the following best describes gravitational force?
A)An attraction between two objects that have mass
B)An attraction between two objects due to their electrons
C)The force that keeps atoms and molecules bound together
D)The force that keeps objects from moving when they are at rest
3. How does distance between two objects affect their gravitational force?
A) Force increases as distance increases.
B)Force decreases as distance increases.
C)Force decreases as distance decreases.
D)Force is not related to distance.
4. Imagine you are an astronaut and you travel to a planet with a much larger mass than Earth. How would this affect your weight? Explain your answer.
C)Weight
A)An attraction between two objects that have mass
B)Force decreases as distance increases.
grav force of massive planet increases your weight
Answer:
C)Weight
A)An attraction between two objects that have mass
B)Force decreases as distance increases.
Explanation:
process where sediment and other material is moved from one place to another is called blank?
An atom with 7 protons, 6 neutrons, and 7 electrons has an atomic mass of _____ amu. (Enter a whole number.)
A boat sails along the shore. To an observer, the boat appears to move at a speed of 22 m/s, and a man on the boat walking forward appears to have a speed of 23.1 m/s. How long does it take the man to move 3 m relative to the boat?
What is the periodic table of elements?
Question 5 options:a chart that organizes all the elements by their atomic number a chart that organizes all the naturally-occuring elements a chart that organizes all the elements by their atomic mass a chart that organizes all the elements created by humansBased on the diagram, which of these conclusions is correct? The frequency of Wave 1 is double the frequency of Wave 2. The frequency of Wave 2 is double the frequency of Wave 1. The wavelength of Wave 1 is four times the wavelength of Wave 2. The wavelength of Wave 2 is four times the wavelength of Wave 1.
Answer: The frequency of Wave 2 is double the frequency of Wave 1.
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Which would be the best element to use in a semiconductor?
Question 5 options:
lithium (Li)
chlorine (Cl) )
silicon (Si)
carbon (C)
what i the difference between a wedge and an inclined plane
Magnet A and B are of equal magnetic strength and which position will magnets A&B have the greatest attraction for toward each other
Explain mass defect in terms of atomic mass number and atomic mass and explain how gamma radiation is produced.
From which sphere does most water evaporate?
A. Lithosphere
B. Hydrosphere
C. Biosphere
D. Atmosphere
What is the mass of an object that weighs 55N on earth?
With Earth's gravity being [tex]9.80 m/s^2[/tex] the mass is approximately 5.61 kg.
To calculate the mass of an object that weighs 55N on Earth, we need to use the formula for weight, which is w = mg, where w is weight, m is mass, and g is the acceleration due to gravity.
On Earth, g is typically [tex]9.80 m/s^2[/tex]
Therefore, we can find the mass of an object by dividing its weight by this acceleration due to gravity.
To calculate the mass (m) of an object that weighs 55N on Earth:
m = w / g
[tex]m = 55 N / 9.80 m/s^2[/tex]
This calculation results in a mass of approximately 5.61 kg.
The Sierra Nevadas are an example of a fault-block mountain range. Based on this information, which of the following processes formed the Sierra Nevadas?
Answer:
Explanation:
The uplift caused a wide range of elevations and climates in the Sierra Nevada, which are reflected by the presence of five life zones (areas with similar plant and animal communities).
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Light from a distant star has undergone a red shift. Which of these conclusions is correct about the star? Its pitch is increasing. Its parallax is increasing. It is moving towards Earth. It is moving away from Earth.
Answer:
It is moving away from Earth.
Explanation:
As the source comes closer to the observer then we can say that its frequency will increase.
So here we know that
[tex]\frac{\Delta \nu}{\nu} = \frac{v}{c}[/tex]
here we know that
v = speed of the star
c = speed of light
now if we know that speed of the star is towards us then the frequency will increase and hence the wavelength will decrease.
So it is known as Blue shift
While if the star is moving away from us then in that case the frequency will decrease and hence the wavelength will increase.
So here it is known as Red Shift.
So here correct answer will be
It is moving away from Earth.
please do the Venn diagram
what is the shape of the orbit of satellites
Answer:
The shape will be elliptical hopefully this helps!
When the moon is waning, what do we see?
A. none of the moon is visible
B. more and more of the moon
C. a full moon
D. less and less of the moon
Answer:
D. Less and less of the moon.
Explanation:
Waning has the meaning decreasing. A waning moon is the moon that decreases in size and its illumination . Moon starts waning a day after the full moon. Its size keeps decreasing and ultimately it is not visible on the new moon day .
A day after the new moon, it starts increasing in size and brightness and is slowly visible each night, until it is completely shining on the full moon day again. This is the waxing of the moon, where its size keeps increasing.
Which formula can be used to find tangential speed of an orbiting object?
Answer:
A) [tex]v = \frac{2\pi r}{T}[/tex]
Explanation:
As we know that the speed of the object is defined as the the ratio of total distance and total time taken
now as we know that here the distance along the path of the orbiting object is total length of the circle
so it is given as
[tex]L = 2\pi r[/tex]
also we know that
time period to complete the orbit is given as
[tex]t = T[/tex]
now the speed is given as
[tex]v = \frac{d}{t}[/tex]
[tex]v = \frac{2\pi r}{T}[/tex]
According to its periodic table entry, how many electrons does nitrogen have in its valence level? 2 5 7 14
Why was the Constitution written, according to the Preamble? A. to create a more perfect Union B. to end slavery C. to break free from Britain D. to give women the vote
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Which direction will the molecules pass through the cell membrane?
a. From bottom to top
b. From left to right
c. From right to left
d. From top to bottom
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C. What organelle is missing from E. coli?
Answer:
The organelle missing from E.coli is nuclear membrane.
Explanation:
A nuclear membrane is a double membrane that surrounds and protects the nucleus of a cell. The nuclear membrane is lacking because there is no need for one to protect a nucleus that does not exist. Bacteria cells are also prokaryotes, and all prokaryotes lack a nucleus.
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What best describes the degree to which a material can transmit heat
- melting point
- boiling point
- thermal conductivity
- electrical conductivity
The correct answer is C. Thermal conductivity
Explanation:
Conduction occurs as heat, electricity, etc. are transmitted from one body to another. In the case of thermal conductivity, this refers to the property of one material or body to transmit or conduct heat. This property is measured in Watts (energy) per meter(distance)-Kelvin (temperature). For example, the thermal conductivity of copper is around 385 while the one of ice is 1.6, which indicates copper has a higher capability to conduct heat. Thus, the degree to which a material can transmit heat is thermal conductivity.
Which statement accurately describes what happens when water turns to steam in terms of energy?
A.The water absorbs energy which causes chemical bonds to break, changing water to steam.
B. The water releases energy which causes the water molecules to have less kinetic and potential energy, changing their configuration from liquid to gas.
C. The water releases energy which causes chemical bonds to break, changing water to steam.
D. The water absorbs energy which causes the water molecules to have more kinetic and potential energy, changing their configuration from a liquid to a gas.
C. The water releases energy which causes chemical bonds to break, changing water to steam.
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Answer:
D The water absorbs energy which causes the water molecules to have more kinetic and potential energy, changing their configuration from a liquid to a gas.
Explanation:
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The water absorbs energy which causes the water molecules to have more kinetic and potential energy, changing their configuration from a liquid to a gas. The correct option is D.
What is kinetic energy?The energy an object has as a result of motion is known as kinetic energy. A force must be applied to an object in order to accelerate it.
We must put in effort in order to apply a force. After the work is finished, energy is transferred to the item, which then moves at a new, constant speed.
Energy is absorbed by the water, increasing the kinetic and potential energy of the water molecules and converting them from a liquid to a gas.
Water molecules usually have the highest kinetic energy in the steam phase.
Thus, the correct option is D.
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Calculate the acceleration of a car that begins at rest at a stop light and accelerates to a speed of 20m/s in a 10 sec time period. Be sure to include the acceleration formula and the final units.