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docker41 [41]
3 years ago
6

What did ancient astronomers think areas of the moon called mares might be?

Physics
1 answer:
Bumek [7]3 years ago
4 0

The ancient astronomers think areas of the moon called mares might be Seas.

Option D  

<u>Explanation</u>:

The surface area of Earth's moon is dark, large, and is basaltic plains which are formed by ancient volcanic eruptions. They were dubbed as Maria, "ancient astronomers" who misunderstood them as actual seas. They are less reflective than highlands. Due to their iron-rich composition, they tend to appear dark from the naked eye. The Maria cover approximately about 16% of surface mostly on side that is visible from Earth. The few Maria on side that is too far are much smaller and residing mostly in very large craters. The ancient astronomers mistook the surface area as look like actual seas.

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State the name of the process in each of the following changes of state:
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Answer:

A. Melting

B. Freezing

C. Condensing

D. Boiling

Explanation:

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3 years ago
An object of mass 6.00 kg falls with an aceleration of 8.00 m/s2. The magnitude of air resitance must be ____ N
allsm [11]
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3 years ago
An elevator together with its passengers weights 5000 N. At a certain instant, the tension in its supporting cable is 6000 N. De
gayaneshka [121]
We have to forces acting on the system (elevator+passengers):
1) The weight (W=5000 N), acting downward
2) The cable's tension (T=6000 N), acting upward
So, the two forces have opposite direction. The resultant (in upward direction) will be
F=T-W
And for Newton's second law, the resultant of the forces acting on the system causes an acceleration on the system itself, given by
a= \frac{F}{m}
where m is the mass of the system.

So, we need to find F and m.
The resultant of the forces is
F=T-W=6000 N-5000 N=1000 N
To find m, we can use the weight of the system. In fact, the weight of an object is given by
W=mg
where g=9.81 m/s^2. Solving for m, and using W=5000 N, we find
m= \frac{W}{g}= \frac{5000 N}{9.81 m/s^2}=510 kg

and at this point, we can calculate the acceleration of the system (elevator+people):
a= \frac{F}{m}= \frac{1000 N}{510 kg}=1.96 m/s^2
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8 0
3 years ago
The first law of motion=.....?​
Fed [463]
Every object will remain at rest
7 0
2 years ago
Read 2 more answers
When light of wavelength 240 nm falls on a potassium surface, electrons having a maximum kinetic energy of 2.93 eV are emitted.
olchik [2.2K]

A) We want to find the work function of the potassium. Apply this equation:

E = 1243/λ - Φ

E = energy of photoelectron, λ = incoming light wavelength, Φ = potassium work function

Given values:

E = 2.93eV, λ = 240nm

Plug in and solve for Φ:

2.93 = 1243/240 - Φ

Φ = 2.25eV

B) We want to find the threshold wavelength, i.e. find the wavelength such that the energy E of the photoelectrons is 0eV. Plug in E = 0eV and Φ = 2.25eV and solve for the threshold wavelength λ:

E = 1243/λ - Φ

0 = 1243/λ - Φ

0 = 1243/λ - 2.25

λ = 552nm

C) We want to find the frequency associated with the threshold wavelength. Apply this equation:

c = fλ

c = speed of light in a vacuum, f = frequency, λ = wavelength

Given values:

c = 3×10⁸m/s, λ = 5.52×10⁻⁷m

Plug in and solve for f:

3×10⁸ = f(5.52×10⁻⁷)

f = 5.43×10¹⁴Hz

7 0
3 years ago
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