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siniylev [52]
3 years ago
6

Why do reflecting telescopes usually have a secondary mirror in addition to a primary mirror?

Physics
1 answer:
Gemiola [76]3 years ago
8 0
Once the starlight or moonlight comes down the tube and hits the big main mirror at the bottom, it's reflected, and heads back up the tube, along the same way it came in. But if you're looking through an eyepiece, the eyepiece is on the SIDE of the tube. So you need another small mirror, to catch the focused light before it goes up out of the tube, and send it sideways to the eyepiece.
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Thinking about the winter we missed out on this year. Calvin and his tiger go sledding down a snowy hill. There is friction betw
jarptica [38.1K]

Answer:

a)  W=0, b) Work is negative, c) work is positive and scientific energy variation is positive, d)     the variation of the potential enrgy is negative,

e) total work is positive

Explanation:

Work in physics is defined by the scalar scalar product of force by displacement

          W = F. dx

The bold are vectors; this can be written in the form of the mules of the quantities

          W = F dx cos θ

where θ is the angle between force and displacement.

a) The normal force is perpendicular to the inclined plane which is perpendicular to the displacement, therefore the angle is

         θ = 90         cos 90 = 0

        W=0

In conclusion the work is zero

b) The friction force opposes the displacement whereby the angle is

       θ = 180      cos 190 = -1

        W = - fr d

Work is negative

c) To calculate the change in kinetic energy we use that the work is equal to the variation of the kinetic energy

            m g sin θ  L = ΔK

this magnitude is positive since the angle is zero cos 0 = 1

how the system starts from rest ΔK = Kf -K₀=  + Kf -0

work is positive and scientific energy variation is positive

d) change in potential energy

               The potential energy is is ΔU = Uf -U₀

we fix the reference system in the bases of the plane so Uf = 0

               ΔU = -U₀

         the variation of the potential enrgy is negative

e) The total work is formed by the work of the weight component, the work of the friction force

              W_Total = W_weight - W_roce

as the body moves down

              W_Total> 0

Therefore the total work is positive

3 0
3 years ago
If a roller coaster train has a potential energy of 1,500 J and a kinetic energy of 500 J as it starts to travel downhill, what
DENIUS [597]

Its total mechanical energy is <em>2,000 J</em>.

We don't have enough information to say anything about its heat energy, its chemical energy, or the energy due to any electrical charge it may be carrying or any magnetic field it may have.

6 0
2 years ago
**20points**
polet [3.4K]
B) a new element is formed
3 0
3 years ago
Read 2 more answers
A certain radio wave has a wavelength of 6.0 × 10-2m. What is its frequency in hertz?
rodikova [14]

Answer:

The frequency of the wave is 5 x 10⁹ Hz

Explanation:

Given;

wavelength of the radio wave, λ = 6.0 × 10⁻²m

radio wave is an example of electromagnetic wave, and electromagnetic waves travel with speed of light, which is equal to 3 x 10⁸ m/s².

Applying wave equation;

V = F λ

where;

V is the speed of the wave

F is the frequency of the wave

λ  is the wavelength

Make F the subject of the formula

F = V /  λ

F = (3 x 10⁸) / (6.0 × 10⁻²)

F = 5 x 10⁹ Hz

Therefore, the frequency of the wave is 5 x 10⁹ Hz

8 0
3 years ago
By what means can the internal energy of a closed system increase?.
kirill115 [55]

Answer:

when work is done on the system or heat comes into the system

7 0
2 years ago
Read 2 more answers
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