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,
we see the light from distant galaxies arriving at our telescopes with
longer wavelengths than the light SHOULD have.
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
the observer. The lengthening of the waves on account of that motion
is called the Doppler effect. (The answer to the question is choice-c.)
But that may not be the only way that light waves can get stretched. It's
the only way we know of so far, and so we say that the distant galaxies
are all moving away from us.
From that, we say the whole universe is expanding, and that right there is
one of the strongest observations that we explain with the Big Bang theory
of creation.
Now: If ... say tomorrow ... a competent Physicist discovers another way
for light waves to get stretched after they leave the source, then the whole
"expanding universe" idea is out the window, and probably the Big Bang
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:
It's true that when we look at distant galaxies, we do see their light
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:
When the light from a distant galaxy pours into our telescope, and we
look at it, and we measure its wavelength, and we find that the wavelength
is longer than it should be ... how do we know what it should be ? ? ?
Answer:
h = 13.06 m
Explanation:
Given:
- Specific gravity of gasoline S.G = 0.739
- Density of water p_w = 997 kg/m^3
- The atmosphere pressure P_o = 101.325 KPa
- The change in height of the liquid is h m
Find:
How high would the level be in a gasoline barometer at normal atmospheric pressure?
Solution:
- When we consider a barometer setup. We dip the open mouth of an inverted test tube into a pool of fluid. Due to the pressure acting on the free surface of the pool, the fluid starts to rise into the test-tube to a height h.
- The relation with the pressure acting on the free surface and the height to which the fluid travels depends on the density of the fluid and gravitational acceleration as follows:
P = S.G*p_w*g*h
Where, h = P / S.G*p_w*g
- Input the values given:
h = 101.325 KPa / 0.739*9.81*997
h = 13.06 m
- Hence, the gasoline will rise up to the height of 13.06 m under normal atmospheric conditions at sea level.
Answer:
B) 3.6x 10_6 N/C or D)2.8 x105 N/C
Answer:
1200 W
Explanation:
Power is given by the ratio between work done and time taken:
where W is the work done and t the time taken.
In this problem, W = 3600 J and t = 3.0 s. Therefore, the power in this exercise is
At 10 m/s, it will take
(2 m)/(10 m/s) =
0.2 sto bridge the gap.
_____
However, it will take an additional 0.514 seconds (0.714 s total) for the policeman to land on the building below. The answer depends on the meaning of the question.
