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Juliette [100K]
3 years ago
9

An extraterrestrial "Eratosthenes" performs the equivalent experiment, that Eratosthenes did on Earth, on her/his home world. Sh

e/He measures the angle of the shadow in her/his alien hometown (Alexandria) to be 10 degrees and the distance to the alien well (Syene) to be 500 km. What is the radius that the alien Eratosthenes estimates for her/his planet?
a. 2865 km
b. 9065 km
c. 18024 km
d. 1500 km
e. 31415 km
Physics
1 answer:
Bad White [126]3 years ago
6 0

Answer:

a. 2865 km

Explanation:

Eratosthenes observed that the sun's rays formed a vertical angle of 7º 12 ’. Which confirmed that the Earth was not flat, assuming that it had a spherical shape, using the distance between Alexandria and Siena and the measure of the angle of inclination of the solar rays in Alexandria, calculated the circumference of the Earth.

The calculation was made with a simple rule of three:

angle of inclination of the solar rays——————- distance

               360º                                   ————- Planet circumference

C=\frac{distance*360^\circ}{angle}\\\\C=\frac{500km*360^\circ}{10^\circ}=18000km

And since we know that:

C=2\pi R\\\\R=\frac{C}{2\pi}\\\\R=\frac{18000km}{2\pi}=2865km

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Calculate the mass (in g) of 346 cm³ of polythene. The density of polythene is 0.95 g/cm³. Give your answer to 2 decimal places.
IceJOKER [234]

Answer:

M = 328.70g

Explanation:

From the given values:

V = 346 cm³

M of 1 cm³ of Polythene = 0.95g or 95/100g

Solve:

M = <u>(95×346)</u>

10

= <u>3</u><u>2</u><u>8</u><u>7</u><u>0</u>

100

M = 328.70g

8 0
2 years ago
Two forces, F⃗ 1F→1F_1_vec and F⃗ 2F→2F_2_vec, act at a point. F⃗ 1F→1F_1_vec has a magnitude of 9.20 NN and is directed at an a
marishachu [46]

Answer:

-9.46 N

Explanation:

In order to get the value of the x component of the resultant force, we need to get the value of the x component of each force.

This value will be the projection of the force vector, on the x-axis.

For F₁, as it is directed at an angle of 55.0º above the negative x axis, we can find F₁ₓ just applying the definition of cosine of an angle, as follows:

cos θ = \frac{x}{r}

In this case, x = F₁ₓ, and r = F₁

θ, measured from the positive x axis counterclockwise, is as follows:

θ= 180º-55º = 125º

⇒ F₁ₓ = F₁* cosθ = 9.2 N * cos 125º = -5.28 N

We can repeat the process for F₂, as follows:

For F₂, as it is directed at an angle of 53.3º below the negative x axis, we can find F₂ₓ just applying the definition of cosine of an angle, as follows:

cos θ = \frac{x}{r}

In this case, x = F₂ₓ, and r = F₂

θ, measured from the positive x axis counterclockwise, is as follows:

θ= 180º + 53.3º = 233.3º

⇒ F₂ₓ = F₂* cosθ = 7.00 N * cos 233.3º = -4.18 N

The total component of both forces along the x axis, can be found just adding both components, as follows:

Fₓ = F₁ₓ + F₂ₓ = -5.28 N + -4.18 N = -9.46 N

5 0
3 years ago
Which of these IS an example of balanced forces? A. a book on a shelf B. air rushing out of a balloon C. rolling over and fallin
babunello [35]

Forces are balanced when net force on the object is zero or the sum of all force on the object is zero.

For book kept on a shelf, the weight of the book in down direction is balanced by the normal force on the book by the shelf. hence the book kept on a shelf is an example of balanced force.

In case of air rushing out of balloon , the balloon experience a net force by the air coming out of it.

rolling over and falling off the bed , the object falls under gravity force.

a car speeding up accelerates. since it accelerates , it has net force on it.

3 0
3 years ago
Each time the heart beats,what does it do to the blood
Tom [10]
Your blood runs through your blood stream, every vein in your body. without that heartbeat the blood would not make it to the required places it needs to run to and you will lose oxygen and parts of your body and organs will shut down.
6 0
3 years ago
The product of voltage times amperage is known as what? amperes current resistance power
UNO [17]

The product of (voltage) times (current, in Amperes) is POWER.

5 0
3 years ago
Read 2 more answers
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