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GREYUIT [131]
3 years ago
13

PLS HELP!!! David looks up at the sky several times one night. He notices that the stars appear to move across the sky. Why do t

he stars appear to move?
A. The Moon changes position in the sky.
B. The Earth is rotating on its axis.
C. The Moon moves with the stars.
D. The Sun orbits the Earth.
Physics
1 answer:
Jlenok [28]3 years ago
5 0

Answer:

b

Explanation:

the earth is moving so it  that the stars are moving, but they arnt

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Leto [7]

your answer is *A. *second harmonic.

i just took the test

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4 years ago
If Sarah melts 10g of tin. What mass of melted tin would she have at the end of the experiment?​
Nastasia [14]

Answer:

10g

Explanation:

As the Law of Conservation of Mass states that " Mass can neither be created nor be destroyed in a chemical reaction".

Though melting of tin isn't a chemical change, the same logic is applied here...

Hence,

The mass of tin will be 10 g itself...

7 0
4 years ago
Read 2 more answers
A circular bird feeder 19.0 cm in radius has rotational inertia 0.130 kg·m2. It's suspended by a thin wire and is spinning slowl
soldi70 [24.7K]

Answer:

N₂=20.05 rpm

Explanation:

Given that

R= 19 cm

I=0.13 kg.m²

N₁ = 24.2 rpm

\omega_1=\dfrac{2\pi \times 24.2}{60}\ rda/s

ω₁= 2.5 rad/s

m= 173 g = 0.173 kg

v=1.2 m

Initial angular momentum L₁

L₁ =  Iω₁  - m v r       ( negative sign because bird coming opposite to motion of the wire motion)

Final linear momentum L₂

L₂=  I₂ ω₂

 I₂ = I + m r²

The is no any external torque that is why angular momentum will be conserve

L₁ = L₂

Iω₁  - m v r =  I₂ ω₂

Iω₁  - m v r =  ( I + m r²) ω₂

Now by putting the all values

Iω₁  - m v r =  ( I + m r²) ω₂

0.13 x 2.5 - 0.173 x 1.2 x 0.19 =  ( 0.13 + 0.173 x  0.19²) ω₂

0.325  - 0.0394 = 0.136 ω₂

ω₂ = 2.1 rad/s

\omega_2=\dfrac{2\pi \times N_2}{60}

N₂=20.05 rpm

3 0
3 years ago
A busy chipmunk runs back and forth along a straight line of acorns that has been set out between its burrow and a nearby tree.
Nadusha1986 [10]

Answer:

0.59 seconds

Explanation:

5 0
3 years ago
What happens to an object's gravitational potential energy as it falls from some height?​
saveliy_v [14]

Answer:

Decreases

Explanation:

As an object falls from some height, the gravitational potential energy of the object decreases.

Potential energy is the energy due to the position of a body.

The potential energy is mathematically expressed as:

   Potential energy  = mass x acceleration due to gravity x height

So, potential energy is directly proportional to mass and height.

The higher the mass and height, the more the potential energy.

3 0
3 years ago
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