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Bond [772]
3 years ago
14

Which of these is an example of a chemical change?

Physics
1 answer:
malfutka [58]3 years ago
5 0
A; A chemical change makes a substance that wasn't there before. Moldy cheese has a new substance, color change and an odor.
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From Earth to the center of our galaxy is about 300,000 light years, meaning that light coming from a star in the center of our
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7 0
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How do scientists use the Doppler effect to understand the universe?
professor190 [17]
There's a very subtle thing going on here, one that could blow your mind.

Wherever we look in the universe, no matter what direction we look,
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The only way we know of right now that can cause light waves to get
longer after they leave the source is motion of the source away from
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Now:  If ... say tomorrow ... a competent Physicist discovers another way
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theory along with it !


Now that our mind has been blown, come back down to Earth with me,
and I'll give you something else to think about:

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arriving in our telescopes with longer wavelengths than it should have.
And then we use the Doppler effect to calculate how fast that galaxy
is moving away from us.  That's all true.  Astronomers are doing it
every day.                                   I mean every night.

So here's the question for you to think about ... maybe even READ about:

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6 0
3 years ago
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Pushing a chair is a law of______?
Valentin [98]
I believe your answer would be A. Due to the friction of pushing the chair while it’s on the floor
8 0
3 years ago
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Two small nonconducting spheres have a total charge of 93.0 μC . Part A
Travka [436]

Answer:

charge on each

Q1 = 2.06 ×10^{-5}  C

Q2 = 7.23 × 10^{-5} C

when force were attractive

Q1 = 1.07 × 10^{-4} C

Q2 = -1.39 × 10^{-5} C

Explanation:

given data

total charge = 93.0 μC

apart distance r  = 1.14 m

force exerted  F = 10.3 N

to find out

What is the charge on each and What if the force were attractive

solution

we know that force is repulsive mean both sphere have same charge

so total charge on two non conducting sphere is

Q1 + Q2 = 93.0 μC  = 93 ×10^{-6} C

and

According to Coulomb's law force between two sphere is

Force F = \frac{K Q1 Q2 }{r^2}      .........1

Q1Q2 = \frac{F*r^2}{k}

here F is force and r is apart distance and k is 9 × 10^{9} N-m²/C² put all value we get

Q1Q2 = \frac{ 10.3*1.14^2}{9*10^9}

Q1Q2 = 1.49 ×  10^{-9} C²

and

we have  Q2 = 93 ×10^{-6} C - Q1

put here value

Q1²  - 93 ×10^{-6}  Q1 + 1.49 ×  10^{-9} = 0

solve we get

Q1 = 2.06 ×10^{-5}  C

and

Q1Q2 = 1.49 ×  10^{-9}

2.06 ×10^{-5}  Q2 = 1.49 ×  10^{-9}

Q2 = 7.23 × 10^{-5} C

and

if force is attractive we get here

Q1Q2 = - 1.49 ×  10^{-9} C²

then

Q1²  - 93 ×10^{-6}  Q1 - 1.49 ×  10^{-9} = 0

we get here

Q1 = 1.07 × 10^{-4} C

and

Q1Q2 = - 1.49 ×  10^{-9}

2.06 ×10^{-5}  Q2 = - 1.49 ×  10^{-9}

Q2 = -1.39 × 10^{-5} C

5 0
3 years ago
A 4kg book sits on a table and your pet hamster puts his front paws on the book and pushes down with a force of 3N. What is the
Natali [406]
There are three forces acting on the book. 
1. Force due to gravity
2. Force exerted downward by the hamster
3. Normal Force in reaction to the downward forces

Since the book is not moving, the net force is zero. The summation of all forces must be zero. Then we could find the normal force which is unknown (denoted as x).

∑F = -(4 kg)(9.81 m/s2) - 3 N + x =0
∑F = -39.24 N - 3N + x =0
x = 42 N

Therefore, the normal force is 42 N.
4 0
4 years ago
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