Help on Astronomy Questions Part II

Thanks to those who replied last week. I got an 85 due in part to your
input. I have more questions. I have my answers. I just want to make
sure I'm right.

1a. The Earth orbits the Sun at a distance of 1 AU. Suppose the Earth
were moved to a distance of 5 AU from the Sun. Would the gravitational
force of the Sun on the Earth be stronger or weaker?

F = 6.67 x 10^11 [ 5.98 x 10^24 x 1.99 x 10^30/ (7.5 x 10^11)^2
F = .141 x 10 ^ 22 3.53 x 10^22 / .141 x 10^22 = 25X weaker

1b. Now suppose that , in addition to being moved farther away, Earth's
mass is increased to five times its original mass. Would the
gravitational force of the Sun on the Earth be stronger or weaker than
it is now? How much stronger or weaker?

F = 6.67 x 10^11 [ 5 x 5.98 x 10^24 x 1.99 x 10^30/ (7.5 x 10^11)^2
F = .7055 x 10 ^ 22 3.53 x 10^22 / .7055 x 10^22 = 5 X weaker

1c. Would you weigh more or less on the Earth if it has five times more
mass like in part b)? How much more or less? You would weigh 5 X
more.

F = 6.67 x 10^11 [ 5 x 5.98 x 10^24 x 1.99 x 10^30/ (1.5 x 10^11)^2
F = .17.64 x 10 ^ 22 17.64 x 10 ^ 22 / 3.53 x 10 ^ 22 = 5 X

2a. List the main regions (or bands) of the electromagnetic spectrum in
order from low to high frequency. 1. radio waves 2. microwaves 3.
infrared 4. visible light 5. ultraviolet 6. X-rays 7. gamma rays

2b. Which region has the shortest wavelength
gamma

2c. Which region has the photons of the highest energy?
gamma

2d. Which of the visible light types has the shortest wavelength?
violet

2e. You are given two monochromatic light sources. Source 1 emits
light at a wavelength of 700nm and source 2 emits light at a wavelength
of 350 nm. Which source emits the highest frequency light? How uch
higher than the other?

f1 = 1/700 x 10 ^ -9 m = 1.43MHZ f2 = 1/350 x 10 ^ -9 m = 2.46MHZ

Source 2 emits the highest frequency light. Twice than the other.

2f. Which, if either, color would move faster through a vacuum?

Both travel at the same speed through a vacuum.

3. According to Newston's Laws, in which direction would Earth move if
the Sun suddently disappeared?

In a straight line along a tangent to its nearly circular orbit.

5. According to Wien's Law, as a new star evolves from a cool cloud of
gas to a hot star, the peak wavelength of its spectrum of
electromagnetic radiation moves toward the shorter wavelengths.


Thanks for your consideration

"azazel scratch" wrote in message
...

Azazel, Don't post in HTML on an ASCII newsgroup. Only trolls do that.


Thanks to those who replied last week. I got an 85 due in part to your
input.
We only got 85??? Heck we should have got much more :-)

I have more questions. I have my answers. I just want to make sure I'm
right.
1a. The Earth orbits the Sun at a distance of 1 AU. Suppose the Earth were
moved to a distance of 5 AU from the Sun. Would the gravitational force of
the Sun on the Earth be stronger or weaker?

Weaker, as per the inverse square law. I'm not going to do your maths :-)

azazel scratch wrote in
:

Thanks to those who replied last week. I got an 85 due in part to
your input. I have more questions. I have my answers. I just want
to make sure I'm right.

1a. The Earth orbits the Sun at a distance of 1 AU. Suppose the Earth
were moved to a distance of 5 AU from the Sun. Would the
gravitational force of the Sun on the Earth be stronger or weaker?

F = 6.67 x 10^11 [ 5.98 x 10^24 x 1.99 x 10^30/ (7.5 x 10^11)^2
F = .141 x 10 ^ 22 3.53 x 10^22 / .141 x 10^22 = 25X weaker

1b. Now suppose that , in addition to being moved farther away,
Earth's mass is increased to five times its original mass. Would the
gravitational force of the Sun on the Earth be stronger or weaker than
it is now? How much stronger or weaker?

F = 6.67 x 10^11 [ 5 x 5.98 x 10^24 x 1.99 x 10^30/ (7.5 x 10^11)^2
F = .7055 x 10 ^ 22 3.53 x 10^22 / .7055 x 10^22 = 5 X
weaker

1c. Would you weigh more or less on the Earth if it has five times
more mass like in part b)? How much more or less? You would weigh
5 X more.

F = 6.67 x 10^11 [ 5 x 5.98 x 10^24 x 1.99 x 10^30/ (1.5 x 10^11)^2
F = .17.64 x 10 ^ 22 17.64 x 10 ^ 22 / 3.53 x 10 ^ 22 = 5 X

2a. List the main regions (or bands) of the electromagnetic spectrum
in order from low to high frequency. 1. radio waves 2. microwaves
3. infrared 4. visible light 5. ultraviolet 6. X-rays 7. gamma
rays

2b. Which region has the shortest wavelength
gamma

2c. Which region has the photons of the highest energy?
gamma

2d. Which of the visible light types has the shortest wavelength?
violet

2e. You are given two monochromatic light sources. Source 1 emits
light at a wavelength of 700nm and source 2 emits light at a
wavelength of 350 nm. Which source emits the highest frequency light?
How uch higher than the other?

f1 = 1/700 x 10 ^ -9 m = 1.43MHZ f2 = 1/350 x 10 ^ -9 m = 2.46MHZ

Source 2 emits the highest frequency light. Twice than the other.

2f. Which, if either, color would move faster through a vacuum?

Both travel at the same speed through a vacuum.

3. According to Newston's Laws, in which direction would Earth move
if the Sun suddently disappeared?

In a straight line along a tangent to its nearly circular orbit.

5. According to Wien's Law, as a new star evolves from a cool cloud
of gas to a hot star, the peak wavelength of its spectrum of
electromagnetic radiation moves toward the shorter wavelengths.


Thanks for your consideration

Uh uh... we might be willing to give a little help here and there, but we
don't do your homework for you.

And please don't post in HTML to and ASCII newsgroup.

azazel scratch wrote:

Thanks to those who replied last week. I got an 85 due in part to
your input. I have more questions. I have my answers. I just
want to make sure I'm right.

1a. The Earth orbits the Sun at a distance of 1 AU. Suppose the
Earth were moved to a distance of 5 AU from the Sun. Would the
gravitational force of the Sun on the Earth be stronger or weaker?

F = 6.67 x 10^11 [ 5.98 x 10^24 x 1.99 x 10^30/ (7.5 x 10^11)^2
F = .141 x 10 ^ 22 3.53 x 10^22 / .141 x 10^22 = 25X
weaker


You don't really need to work out the force to answer questions like
this, because it's only the ratio in the two situations that's of
concern. That is, if you write

F2/F1 = (GMm/(5R)^2)/(GMm/R^2) = R^2 / 25R^2 = 1/25

all the masses &c. cancel out.

[snip some questions, all answers fine]

2e. You are given two monochromatic light sources. Source 1 emits
light at a wavelength of 700nm and source 2 emits light at a
wavelength of 350 nm. Which source emits the highest frequency
light? How uch higher than the other?

f1 = 1/700 x 10 ^ -9 m = 1.43MHZ f2 = 1/350 x 10 ^ -9 m = 2.46MHZ

Source 2 emits the highest frequency light. Twice than the other.


Your conclusion is correct, but the frequencies are wrongly
expressed. The megahertz band is in the radio part of the spectrum:
in fact your first figure might belong to a commercial AM station,
"1430 (kHz) on your dial". The values you calculated aren't in fact
MHz, but rather inverse metres (m^-1) -- still, their ratio remains
the same. As above, if you were to write

1/L2 / 1/L1 = L1/L2 = 700 nm / 350 nm = 2,

you needn't work out the actual frequencies.

But for E-M radiation _in vacuo_, nu * lambda = c, where nu is the
frequency, lambda is the wavelength, and c is the speed of light --
which last is the 'missing factor' to turn m^-1 into Hz in your
answer. So for the 700-nm source

nu = 3*10^8 m/s / 7*10^-7 m = 0.428*10^15/s = 428 THz (terahertz).

Inverse metres are an acceptable unit for frequency, sometimes used
in spectrography &c., but they mustn't be confused with hertz. Always
check your dimensions: they're at least as important as the numerical
part of any physics calculation.

--
Odysseus

Paul Lawler wrote:

azazel scratch wrote in
:

Thanks to those who replied last week. I got an 85 due in part to
your input. I have more questions. I have my answers. I just want
to make sure I'm right.

[snip]

Uh uh... we might be willing to give a little help here and there, but we
don't do your homework for you.

Where did you get the idea that's what he's asking for? Although his
posting style is a little hard to follow, he provided answers to all
the questions -- and AFAICT got them all right, because the mistakes
he made were all in his 'extra work'.

And please don't post in HTML to and ASCII newsgroup.

And please don't quote an entire message to make a three-line reply.

--
Odysseus