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4 years ago

What instrument did navigators use to calculate the positions of the sun and the stars?

Physics

2 answers:

Taya2010 [7]4 years ago

8 0

Navigators used astrolabes to calculate positions of the sun and stars.

lakkis [162]4 years ago

7 0

Answer:

An Astrolabe

Explanation:

As we know that we need to find the positions of Sun and Stars

So here we will analyze the given options

1) A Caravel

2) A Carrack

above both are two different types of Sailing ships so they can not be the answers as we can not measure the positions of sun and star with the help of ship

4) Compass

It is magnetic needle placed in horizontal plane and it is used to find out the directions and worked on the magnetic field of Earth

3) An Astrolabe

This devise is used to find out the position of Sun and other Celestial bodies and used by astronomers in past time

so correct answer will be

An Astrolabe

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A 25 Kg rock is sitting on a cliff that is 50 meters above the ground. If it fell off of the cliff, and all energy was conserved

svetlana [45]

Answer:

v = 31.32 [m/s]

Explanation:

To solve this problem we must use the principle of energy conservation, which tells us that potential energy is converted into kinetic energy or vice versa. The potential energy can be calculated by the product of mass by gravity by height.

$E_{pot}=m*g*h$

where:

Epot = potential energy [J]

m = mass = 25 [kg]

g = gravity acceleration = 9.81 [m/s²]

h = elevation = 50 [m]

Now replacing:

$E_{pot}=25*9.81*50\\E_{pot}= 12262.5[J]$

When the rock falls the potential energy is converted into kinetic energy.

$E_{pot}=E_{k}\\E_{k}=\frac{1}{2}*m*v^{2}$

where:

Ek = kinetic energy [J]

v = velocity [m/s]

Now clearing v:

$v^{2} =\frac{E_{k}*2}{m}\\v=\sqrt{(2*12262)/25}\\v = 31.32 [m/s]$

8 0

3 years ago

Suppose that we use a heater to boil liquid nitrogen (N2 molecules). 4480 J of heat turns 20 g of liquid nitrogen into gas. Note

love history [14]

Answer:

The energy is $9.4\times10^{-21}\ J$

(a) is correct option

Explanation:

Given that,

Energy = 4480 j

Weight of nitrogen = 20 g

Boil temperature = 77 K

Pressure = 1 atm

We need to calculate the internal energy

Using first law of thermodynamics

$Q=\Delta U+W$

$Q=\Delta U+nRT$

Put the value into the formula

$4480=\Delta U+\dfrac{20}{28}\times8.314\times77$

$\Delta U=4480-\dfrac{20}{28}\times8.314\times77$

$\Delta U=4022.73\ J$

We need to calculate the number of molecules in 20 g N₂

Using formula of number of molecules

$N=n\times \text{Avogadro number}$

Put the value into the formula

$N=\dfrac{20}{28}\times6.02\times10^{23}$

$N=4.3\times10^{23}$

We need to calculate the energy

Using formula of energy

$E=\dfrac{\Delta U}{N}$

Put the value into the formula

$E=\dfrac{4022.73}{4.3\times10^{23}}$

$E=9.4\times10^{-21}\ J$

Hence, The energy is $9.4\times10^{-21}\ J$

4 0

3 years ago

Our atmosphere exerts a pressure of 14.7 lb/in2. What is the force on one square foot of the earth’s surface caused by the atmos

Studentka2010 [4]

Answer:

The force on one square foot of the earth’s surface caused by the atmosphere is 101.4 kN.

Explanation:

To force is given by:

$F = P*A$ (1)

Where:

P: is the pressure = 14.7 lb/in²

A: is the area = 1 m²

By entering the above values into equation (1) we have:

$F = P*A = 14.7 \frac{lb}{in^{2}}*\frac{4.45 N}{1 lb}*\frac{1550 in^{2}}{1 m^{2}}*1 m^{2} = 101.4 kN$

Therefore, the force on one square foot of the earth’s surface caused by the atmosphere is 101.4 kN.

I hope it helps you!

3 0

3 years ago

Aurora binge drinks. what does this most likely mean for aurora? a she drinks enough alcohol to become intoxicated. b she only d

Oksanka [162]

The most likely mean for aurora. She drinks one or two drinks every night. Option C is correct.

<h3>What is Binge-drinking?</h3>

Binge-drinking is explained as having five or more drinks in one sitting for males, and four or more drinks in one sitting for women.

The majority of people who binge-drink do not have a serious alcohol problem. Binge-drinking, on the other hand, is a dangerous risk behavior linked to significant injuries and a variety of disorders.

Hence, option C is correct.

To learn more about the binge-drinking, refer to the link;

brainly.com/question/8049036

#SPJ1

3 0

2 years ago

In an experiment, a ringing bell is placed in a vacuum jar that does not have any air in it. What best describes why the bell is

madam [21]

Answer:

Light does not need a medium to travel travel through, but since waves must have a medium to vibrate, sound is not created where no air is present.

Explanation:

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3 years ago