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3 years ago

11. Reflecting telescopes are popular because they're _______ than a refracting telescope.

2 answers:

4 0

I do not know what the school expects as an answer, but advantage of reflecting telescopes is that there is only one major reflecting surface, so it is quite easy to create a 6 or 8 inch telescope by an amateur, after adding on a prism and an eyepiece. (a microscope eyepiece could be used).
MY answer would be "easier to build". (it still takes tens of hours to grind and polish the single plane surface to a parabolic surface).

Electromagnetic waves all have the same velocity in the same medium. However, since frequencies vary widely, so do wavelengths.

lyudmila [28]3 years ago

4 0

for 11. the answer is they are D. easier to build. hope i helped (:

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Vector A= 3.7 i + 1.0 j and vector B = 3.0 i + 6.5 j. What is vector<br> (A-B).A?

kicyunya [14]

Answer:

(A - B).A = -2.91

Explanation:

First, let's define the sum and dot product of vectors.

For two vectors V = (x₁, y₁) and W = (x₂, y₂) we have:

sum (or subtraction):

V + W = (x₁, y₁) + (x₂, y₂) = (x₁ + x₂, y₁ + y₂)

dot product:

V.W = (x₁, y₁).(x₂, y₂) = x₁*x₂ + y₁*y₂

Here remember the notation:

V = x₁*i + y₁*j = (x₁, y₁)

Now let's solve our problem, we have:

A = (3.7, 1.0)

B = (3.0, 6.5)

Then:

(A - B).A = ( (3.7, 1.0) - (3.0, 6.5) ).(3.7, 1.0)

= (3.7 - 3.0, 1.0 - 6.5).(3.7, 1.0)

= (0.7, -5.5).(3.7, 1.0) = (0.7*3.7) + (-5.5)*(1.0) = -2.91

8 0

3 years ago

I DO NOT WANT LINKES OR …………..

il63 [147K]

1st B is correct option

2nd D is correct option

4 0

3 years ago

Read 2 more answers

The Earth orbits the Sun with a period of 3.16 x 107 seconds (1 year!) at a distance of 1.5 x 1011 m. The mass of the Earth is 6

SVETLANKA909090 [29]

Answer:

a) M = 2 10³⁰ kg , b) $T_{m}$ = 5.81 10⁷ s

Explanation:

a) For this exercise let's use Newton's second law where force is the law of universal gravitation and acceleration is centripetal

G m M / R² = m a

a = v² / R

G M / R = V²

The orbit of the two planets is approximately circular, therefore the velocity module (speed) is constant

v = d / t

The distance is the length of the circular orbit

d = 2π R

G M / R = 4π² R² / T²

G M T² = 4π² R³

Let's write this equation for each planet

For the earth

The period is T = 3.16 10⁷ s and the radius of the orbit R = 1.5 10¹¹ m, let's calculate the mass of the sun

M = 4π² R³ / G T²

M = 4π² (1.5 10¹¹)³ / (6.67 10⁻¹¹ (3.16 10⁷)²)

M = 133.24 10³³ / 66.60 10³

M = 2 10³⁰ kg

b) For this part we write this equation for the two points

For the earth

$T_{E}$ ² = (4π² / G M) $R_{E}$ ³

For mars

$T_{m}$ ² = (4π² / G M) $R_{m}$ ³

Let's divide the two expressions

$T_{m}$ ² / $T_{E}$ ² = $R_{m}$ ³ / $T_{E}$ ³

They indicate that the orbit of Mars is $R_{m}$ = 1.5 $R_{E}$

$T_{m}$ ² / $T_{E}$ ² = (1.5 $R_{E}$ / $R_{E}$ )³

$T_{m}$ ² = $T_{E}$ ² 1.5³

$T_{m}$ ² = (3.16 10⁷)² 1.5³

$T_{m}$ = √ (33.70 10¹⁴)

$T_{m}$ = 5.81 10⁷ s

5 0

3 years ago

What is the color of visible light of the lowest frequencies? Of the highest frequencies?

Genrish500 [490]

lowest frequncy:red

highest frequency:violet

6 0

4 years ago

During a circus act, one performer swings upside down hanging from a trapeze holding another, also upside-down, performer by the

Romashka-Z-Leto [24]

Answer: 1.65 x 10^-5 m

Explanation:

Using the equation

Delta L = (1/Y x F/A ) Lo

Y = 1.6 x 10^10 N/m^2

Lo = 0.31 m

A= pi x r^2 = pi x (0.0178m)^2 = 9.9 x 10^ - 4 m^2

Ftot = 3 x w = 3 x 55 x 9.8 = 1617N

Fleg = Ftot/2 = 1617/2 = 808.5N

Delta L = 1/1.6 x 10^10 x 808.5/9.9 x 10^-4 x 0.31

= 0.65 x 10^-10 x 81.7 x 10^4 x 0.31 = 1.65 x 10^-5 m

The fire leg is stretched by 1.65 x 10^-5 m

4 0

4 years ago