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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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The Eiffel Tower is a steel structure whose height increases by 19.4 cm when the temperature changes from -9 to 41 oC. What is t

RUDIKE [14]

Answer:

Initial height L = 323.3m

Explanation:

Given:

Change in Length ∆L = 19.4cm 0.194m

Change in temperature ∆T = 41 -(-9) = 50°C

Coefficient of linear Thermal expansion of steel k = 12 × 10^-6 m/mK

Using the formula for linear expansion:

∆L = Lk∆T

L = ∆L/k∆T ....1

Substituting the given values into equation 1

L = 0.194/(12 × 10^-6 × 50)

Initial height L = 323.3m

7 0

3 years ago

If we double only the amplitude of a vibrating ideal mass-and-spring system, the mechanical energy of the system:

Lelechka [254]

Answer:

D. increases by a factor of 4.

Explanation:

General equation of SHM

Lets taken the general equation of the displacement given as

x = A sinω t

A=Amplitude ,t=time ,ω=natural frequency

We know that speed V

$V=\dfrac{dx}{dt}$

V= A ω cosωt

The mechanical energy of spring mass system

$U=\dfrac{1}{2}KA^2$

K=Spring constant

Now when Amplitude A become 2 times then the mechanical energy will become 4 times.

Therefore the answer is D.

8 0

3 years ago

How much time is needed to produce 900 Joules of work if 120 watts of power is used?

Charra [1.4K]

Answer:

7.5 seconds

Explanation:

because wattsXtime=Joules so 120X__=900. 900 divided by 120= 7.5

6 0

3 years ago

What is the difference between pulse and periodic waves, and what is the difference between transverse and longitudinal waves?

stiv31 [10]

<u>Difference between pulse and periodic waves:</u>

A pulse wave is a sudden disturbance in which only one wave or a few waves are generated, such as in the example of the pebble. Thunder and explosions also create pulse waves. A periodic wave repeats the same oscillation for several cycles, such as in the case of the wave pool, and is associated with simple harmonic motion. Each particle in the medium experiences simple harmonic motion in periodic waves by moving back and forth periodically through the same positions.

<u>Difference between longitudinal and transverse waves:</u>

A transverse wave propagates when the disturbance is perpendicular to the propagation direction. An example of a transverse wave is where a woman moves a toy spring up and down, generating waves that propagate away from herself in the horizontal direction while disturbing the toy spring in the vertical direction.

In a longitudinal wave, the disturbance is parallel to the propagation direction. Example of longitudinal wave is where the woman now makes a disturbance in the horizontal direction—which is the same direction as the wave propagation—by stretching and then compressing the toy spring.