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Pavlova-9 [17]
3 years ago
12

Astronomical observatories have been available since ancient times, and many cultures set aside special sites for astronomical o

bservations. The thing modern observatories have that was missing from these older observatories until about 1610 was __________________. Group of answer choices
Physics
1 answer:
Vlada [557]3 years ago
8 0

Answer:

The answer is "telescopes".

Explanation:

Throughout ancient times, astronomical observatories have indeed been available, and so many historical locations were reserved for astronomical observations. All contemporary astronomers lacked within those older telescopes were lenses until 1610. A telescope is indeed an instrument used to view far-off objects. Telescopes often are being used to look at planets and stars.

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A plastic tube allows a flow of 15.9 cm3 /s of water through it. how long will it take to fill a 237 cm3 bottle with water? answ
xxMikexx [17]
You are given a fixed rate of 15.9 cm³/s. You are also given with the amount of volume in 237 cm³. Through the approach of dimensional analysis, you can manipulate through operations such that the end result of the units must be in seconds. The solution is as follows:

237 cm³ * (1 s/15.9 cm³) = 14.9 seconds
7 0
3 years ago
An electric heater is rated 1000watts. If a current of 5A pass through the heater, find the value of its resistance.​
ICE Princess25 [194]

Answer: R=40 Ω

Explanation: P=I^{2} R

R=1000/ (25)=40

5 0
3 years ago
A modern compact fluorescent lamp contains 1.4 mg of mercury (Hg). If each mercury atom in the lamp were to emit a single photon
Reika [66]

Answer:

A. 1.64 J

Explanation:

First of all, we need to find how many moles correspond to 1.4 mg of mercury. We have:

n=\frac{m}{M_m}

where

n is the number of moles

m = 1.4 mg = 0.0014 g is the mass of mercury

Mm = 200.6 g/mol is the molar mass of mercury

Substituting, we find

n=\frac{0.0014 g}{200.6 g/mol}=7.0\cdot 10^{-6} mol

Now we have to find the number of atoms contained in this sample of mercury, which is given by:

N=n N_A

where

n is the number of moles

N_A=6.022\cdot 10^{23} mol^{-1} is the Avogadro number

Substituting,

N=(7.0\cdot 10^{-6} mol)(6.022\cdot 10^{23} mol^{-1})=4.22\cdot 10^{18} atoms

The energy emitted by each atom (the energy of one photon) is

E_1 = \frac{hc}{\lambda}

where

h is the Planck constant

c is the speed of light

\lambda=508 nm=5.08\cdot 10^{-7}nm is the wavelength

Substituting,

E_1 = \frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{5.08\cdot 10^{-7} m}=3.92\cdot 10^{-19} J

And so, the total energy emitted by the sample is

E=nE_1 = (4.22\cdot 10^{18} )(3.92\cdot 10^{-19}J)=1.64 J

4 0
3 years ago
The voltage entering a transformer’s primary winding is 120 volts. The primary winding is wrapped around the iron core 10 times.
loris [4]
<u>Answer</u>

 48 Volts  

<u>Explanation</u>
The question can be solve using the turn rule of a transformer that states;

Np/Ns = Vp/Vs
Where Np ⇒ number of turns in the primary coil.
            Ns ⇒number of turns in the seconndary coil
            Vp ⇒ primary voltage
             Vs ⇒secondary voltage

Np/Ns = Vp/Vs

10/4 = 120/Vp

Vp = (120 × 4)/10

      = 480/10
      = 48 Volts  

 

5 0
4 years ago
Read 2 more answers
1. Which statement about friction is true?(1 point) A. Static friction and kinetic friction in a system always act in the same d
ArbitrLikvidat [17]

Answer:

true 1Ay 2D

Explanation:

1) In this exercise you are asked to investigate which statements are true

A) True. The friction force opposes the movement caused by the external force,

B) False. Mantuano in the opposite direction force

C) False. The static and scientific friction force act in the same direction, since the second appears when the movement does not start and the static friction decreases.

D) Fale the static and kinetic friction forces act in the same direction

2) How to overcome friction on a ramp

A) False. If the texture of the surface becomes rough, the friction force increases

B) False. Pressing the brick against the surface increases the normal and as the friction is proportional to the normal, it also increases

C) False. By lowering the table the weight component in the friction direction decreases

D) True. When lifting the board, the weight component increases and therefore can become greater than the friction

          Wx-fr = ma

           W sin tea - my mg cos tea = m a

As it increases, the sine increases and the cosine decreases.

3 0
3 years ago
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