If have a custom made telescope with these specifications then what's the focal length of my telescope? (refractor telescope only please)

_Specifications:_
*Objective diameter*: 90mm
*Distance between lenses*: 230mm
*Eyepiece focal length*: 4mm
*Eyepiece size*: 31.7mm

Please respond fast. Also please give a simplified answer for a brainliest answer tag. Thanks!​

The crest is the highest point of a pebble-induced ripple in a body of water. Option a is correct.

The distance between two successive troughs or crests is known as the wavelength. The highest point of the wave is the crest, while the trough is the lowest.

The high point of the ripple seen in a pond after throwing in a pebble is the crest.

Hence option a is correct.

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Explanation:

Magnetic stripes provide evidence of seafloor spreading due to their occurrence in the region of sea floor.

When the Earth's magnetic field reverses, a new stripe starts to form. Such magnetic patterns enable the scientist to recognize the occurrence of sea-floor spreading and provides strongest evidence for the theory of plate tectonics.

So we can conclude that magnetic stripes provide evidence of seafloor spreading due to their occurrence in the region of sea floor.

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Explanation:

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The speed of sound waves in air at room temperature T=20° is 344.035 m/s.

The range of wavelength in air to which the human ear (which can hear frequencies in the range of 20 – 20,000Hz) is sensitive is  17.20 m to  0.0172 m.

The wavelength is the distance between the adjacent crest or trough of the sinusoidal wave. The wavelength is the reciprocal of the frequency of the wave.

Wavelength λ = c/f

where c is the speed of sound wave.

Given the room temperature T = 20 +273 = 293K

The velocity of sound wave is given by

v = √(γRT/m)

​where γ =1.4 , m = 28.8×10⁻³ kg/mol  R = 8.31 J/K.mol

Substituting the values, we get

v = 344.035 m/s

Thus, the speed of sound wave is 344.035 m/s

​

The human ear can hear frequencies in the range of 20 – 20,000Hz.

The wavelength corresponding to 20Hz is

λ = c/f

λ =  344.035 /20

λ  = 17.20 m

The wavelength corresponding to 20,000Hz is

λ =  344.035 /20000

λ  = 0.0172 m

Thus, the range of wavelength is 17.20 m to  0.0172 m sensitive to human ear.

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The magnitude of the electric field at x =4m on the x axis at this time 1 N/C.

Electric field at a given distance is calculated as follows;

E = kq/r²

E₂ = (9 x 10⁹ x q)/(2²)

E₂ = 2.25 x 10⁹q

E₂ + E₀ = 0

2.25 x 10⁹q + 4 = 0

2.25 x 10⁹q = - 4

q = -4 / (2.25 x 10⁹)

q = -1.78 x 10⁻⁹

E₄ = (9 x 10⁹ x (-1.78 x 10⁻⁹) ) / (4²)

E₄ = - 1 N/C

|E₄| = 1 N/C

Thus, the magnitude of the electric field at x =4m on the x axis at this time 1 N/C.

The complete question is below:

Suppose a uniform electric field of 4N/C is in the positive x direction. When a charge is placed and at a fixed to the origin, the resulting electric field on the x axis at x =2m becomes zero. What is the magnitude of the electric field at x =4m on the x axis at this time?

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the answer is in the picture ok

good luck don't worry it's a correct

#carry on learning

All elements in the same group have the same number of electrons in the outermost energy level. Option C is correct.

The periodic table is an organization of all known elements in order of increasing atomic number and repeating chemical characteristics.

They are organized in a tabular format, with a row representing an era and a column representing a group. E elements are ordered in increasing atomic number order from left to right and top to bottom.

Thus, Elements of the same group will have the same valence electron configuration and, as a result, will have comparable chemical characteristics.

Each set of elements has an equal amount of electrons in the outer orbital. Valence electrons are another name for the outer electrons.

They are the electrons interacting with other elements in chemical bonding. Each element in group one, the first column, has one electron in its outer shell.

Hence option C is correct.

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Explanation:

hi

please help me. ineed answers

Gerund/Infinitive

1. Put the verbs in brackets into the correct infinitive form or the -ing form.

1. Jane went on____(sleep) for another two hours.

2. He told us his name and went on____ (introduce) us to his wife.

3. She tried (finish) her homework, but it was too difficult.

4. You should try (eat) more fruit. It's good for your health.

5. He regrets (argue) with his best friend.

6.We regret (inform) you that tonight's performance will be cancelled.

7. Oh, no! I forgot____(lock) the front door.

8. I'll never forget_(meet) my favourite film star.

9.Claire likes (ski). She says it's very exciting.

10. I like__(go) to the dentist every six months.

11.I must remember (post) these letters today.

12. I remember__(read) the book, but I don't know who wrote it.

13. I'm sorry for___(forget) your birthday. It was awful of me.

14. I'm sorry.(say) that you have failed the exam.

15. She is afraid___(climb) the tree in case she falls.

16.Mary never wears her diamond ring. She is afraid of (lose) it.

17. I have stopped . (buy) some food before continuing our journey.

18. We stopped (watch) horror films because they give me nightmares

19. Tom stopped__(pick up) his washing on the way home.

20 If you don't stop. (smoke), you'll make yourself ill.

21.Will you quit___(complain)! It doesn't help.___(solve) the problem.

22.If you ever decide___(sell) your car, let me____(know).

23.I would like you.__(water) the plants for me at the weekend.

24.I clearly remember__(set) my alarm clock before__(go) to bed last night.

25. These plants require(water) every day.

26. I resent you (speak) to me like that! Have some respect.

27. It would be good for the children__ (play) outdoors more often.

28. I promised __(take) Jill to the party, but I don't feel like__(go) now.

29. Don't waste your time (look for) the document.Ask Mr Gale.

30. Please, excuse his__(leave) so early. He wants __(catch up) with his (study).

31. Try__(phone) John at the office if he's not at home.

32. I tried my best__(finish), but there just wasn't enough time.

33. He was promoted in 1990 and went on__(become) a company director.

34. The band went on__(play) even after the lights had gone out.

35. "Why is the baby crying?" "I think he wants (feed)."

36. Sharon wants__(talk) to you.

37. Jane was afraid__(show) her school report to her parents.

38. I'm afraid of__(lose) my way in the forest.

39. I regret__ (inform) you that your husband has been arrested.

The correct statement about the sun and the earth is that only about half of the suns energy hits the earths surface.

The sun is the source through which energy reaches the earth. The sun is a large star that produces energy by the process of nuclear fusion.

Hence, the correct statement about the sun and the earth is that only about half of the suns energy hits the earths surface.

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Answer:

Using 3 periods to get an accurate reading:

3T = (6.40 S - 0.90 s) = 5.50 S So, T = 1.83 s

m = 0.250 kg

Using algebra:

k= [tex]\frac{4\pi ^{2}m }{T^{2} }[/tex]=[tex]\frac{4\pi ^{2}0.250 }{1.90^{2} }[/tex]=2.95kg/sec

The initial velocity of the arrow and the height of the building will be 29.05 m/s² and 781 m respectively.

The change of distance with respect to time is defined as speed. Speed is a scalar quantity. It is a time-based component. Its unit is m/sec.

The given data in the problem is;

u is the initial velocity of fall = ?  m/sec

h is the distance of fall = 200 m

g is the acceleration of free fall = 9.81 m/sec²

H is the height of the building

t is the time period = 10 second

According to Newton's second equation of motion,

[tex]\rm h= ut+\frac{1}{2} gt^2 \\\\\ h-\frac{1}{2} gt^2 =ut \\\\ 200 - 0.5 \times(9.81) \times 10^2 = 10 u \\\\ u = - 29.05 \ m/sec[/tex]

- ve shows the direction is downward.The magnitude of the initial velocity is found as;

u = 29.05 m/sec

The height of the building

[tex]\rm H= ut+\frac{1}{2} gt^2 \\\\\ H = 29.05 \times 10 + 0.5 \times 9.81 \times 10^2 \\\\ H = 781 \ m[/tex]

Hence the initial velocity of the arrow and the height of the building will be 29.05 m/s² and 781 m respectively.

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Answer:

Explanation:

Comment

I think the best answer is probably A.  It's not the best reason for Earth loosing it's helium, but it is the only one that is close. The Earth derives some of its Helium (most) by the decomposition process of radio active high weight chemical that break down. Helium combines with practically nothing so once it gets moving, very little will stop it. That's the way we loose our Helium.

Still answer A.

Some words that have changed meaning due to technological advances are dial, type, tweet, drone, and spam.

Answer:

Explanation:

Solution

In physics, a period is a measurement of time. The answer must be either B or C. It is a direct measurement of time, not its reciprocal. So the answer is B. A and D is a measurement of the actual cycle that it takes before the motion begins to repeat itself.

Answer

B

Teacher Cellyn Kyre ensures that her classroom is always ready for the face to face classes​ is the sentence used in  quotas and interviews.

Interview is the examination of the candidate from which a person identifies the candidate is fit for the organization o r not. Maximum interview happened between the interviewer and the candidate. or sometime more people can also be present.

Thus, option D is correct.

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The weight of the object on pluto will be 15.56 N

Newton's law of gravity states that each particle having mass in the universe attracts each other particle with a force known as the gravitational force.

Given data;

[tex]\rm g_e[/tex] is the acceleration due to gravity on earth.

m is the mass of an object

[tex]\rm g_p[/tex] is the acceleration due to gravity on pluto.

[tex]\rm W_e[/tex] is the weight of the object on earth

[tex]\rm W_ p[/tex] is the weight of an object on pluto

The mass of the object on the earth's surface is found as;

We = m × ge

m = W / ge

m = 250 / 9.81

m = 25.51  kg

The weight of the object on pluto.

Wp = m × gp

Wp = 25.51  kg × 0.61  m/s²

Wp =15.56 N.

Hence the weight of the object on pluto will be 15.56 N

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Answer: B.

15.6 newtons

Explanation: edmentum

Answer:

r = 2.0m

when t = 0, the angular displacement is zero.

Explanation:

When the angular acceleration is 0.01 m/s2, you can calculate

angular acceleration = change in angular velocity/ time

The centripetal force is obtained by its formulas is,[tex]\rm F_C= \frac{mv^2}{r}[/tex]

The acceleration needed to move a body in a curved way is understood as centripetal acceleration.

The direction of centripetal acceleration is always in the path of the center of the course. The total acceleration is the result of tangential and centripetal acceleration.

The formula for the centripetal force is ;

[tex]\rm F_C= \frac{mv^2}{r}[/tex]

Where,

r is the radius

v is the linear speed

m is the mass of an object

Hence, the centripetal force obtained by its formulas as,[tex]\rm F_C= \frac{mv^2}{r}[/tex]

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Answer:

( 688.29 , 276.66 )   meters

Explanation:

Break into horizontal and vertical components

x = 100 cos 55  = 57.36 m/s      

   the x coordinate is then 12 seconds * 57.36 m/s = 688.29 meters

y coordinate is a bit more complex because of the curved path due to gravity

Original y velocity =  100 sin 55

y = vo t - 1/2 (9.81)(t^2)

y =  100 sin 55  (12)  - 1/2 (9.81) (12)^2

      yf = 276.66   meters

Answer:

Given - Force = 21.4 N

Work done = 1974 J

To find - Distance

Solution -

Work done = Force * displacement

1974 j = 21.4 N * displacement

1974/21.4 = displacement

92.24

[tex]\\ \rm\Rrightarrow Work=Force\times Displacement [/tex]

[tex]\\ \rm\Rrightarrow 1974=21.4×Displacement[/tex]

[tex]\\ \rm\Rrightarrow Displacement=92.24m[/tex]

The activity of the contaminant will be 3.5 ×10⁻¹⁰ Bq if the contaminant is 1.1MeV Beta Emitter.

Disclaimer, here the m is taken as 0.5kg.

Given, REM = 1500

Time, t= 1 minute =60 seconds

For beta particles,

RBE (Relative Biological Effectiveness) =2.

Absorbed dose,  D =REM/RBE= 1500/2 = 750rad

As 100 rad=1 J/kg,

750 rad=7.5 J/kg

So, D=7.5 J/kg

D= total energy absorbed (E)/mass (m)

7.5 J/kg=E/m

E =7.5 ×0.5 = 3.75J

Therefore, the number of beta particles absorbed is 3.75 J.

The number of beta particles absorbed,

As 1 MeV= 1.6 ×10⁻¹³J

So, converting 1.1 MeV in J, 1.1×1.6 ×10⁻¹³J=1.76×10⁻¹³J

Numbers of beta particles,

n=3.75J/1.76×10⁻¹³J

n=2.13×10⁻¹²

Hence, the number of beta particles is 2.13×10⁻¹².

Activity, A= n/t

where n is the number of beta particles and t is the time.

A= n/t=(2.13×10⁻¹²)/60

A= 3.5 ×10⁻¹⁰ Bq

So, the activity is 3.5 ×10⁻¹⁰ Bq.

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Hence, the time required is approximately equal to 4 minutes and 39 seconds.

Given, Power, P = 300 W= 300J/s

Power= Energy per second

Mass, m= 0.25 kg

Initial Temperature= 20.0°C

Final Temperature= 100.0°C

Temperature difference, T =( 100-20)°C= 80.0°C

Specific heat of water, S= 4184 J/kg°C

Energy can be represented as

E=mST

where E is the energy, m is the mass, S is the specific heat of water and T is the temperature difference.

As Energy can be written as the product of time and power, E=Pt

Pt=mST

So,

t=(msT)/P

t=(0.25×4184×80)/300

Time, t = 278.934 seconds= 4 minutes and 39 seconds.

Hence, 4 minutes and 39 seconds will be required for a 300.0 W immersion heater to heat 0.25 kg of water from 20.0°C to 100.0°C.

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Answer:

i dond no can you put another question

Answer:

Approximately [tex]325[/tex] (rounded down,) assuming that [tex]g = 9.81\; {\rm N \cdot kg^{-1}}[/tex].

The number of repetitions would increase if efficiency increases.

Explanation:

Ensure that all quantities involved are in standard units:

Energy from the cookie (should be in joules, [tex]{\rm J}[/tex]):

[tex]\begin{aligned} & 53\; {\rm kCal} \times \frac{1\; {\rm kJ}}{4.184\; {\rm kCal}} \times \frac{1000\; {\rm J}}{1\; {\rm kJ}} \approx 2.551 \times 10^{5}\; {\rm J} \end{aligned}[/tex].

Height of the weight (should be in meters, [tex]{\rm m}[/tex]):

[tex]\begin{aligned} h &= 2\; {\rm dm} \times \frac{1\; {\rm m}}{10\; {\rm dm}} = 0.2\; {\rm m}\end{aligned}[/tex].

Energy required to lift the weight by [tex]\Delta h = 0.2\; {\rm m}[/tex] without acceleration:

[tex]\begin{aligned} W &= m\, g\, \Delta h \\ &= 100\; {\rm kg} \times 9.81\; {\rm N \cdot kg^{-1}} \times 0.2\; {\rm m} \\ &= 196\; {\rm N \cdot m} \\ &= 196\; {\rm J} \end{aligned}[/tex].

At an efficiency of [tex]0.25[/tex], the actual amount of energy required to raise this weight to that height would be:

[tex]\begin{aligned} \text{Energy Input} &= \frac{\text{Useful Work Output}}{\text{Efficiency}} \\ &= \frac{196\; {\rm J}}{0.25} \\ &=784\; {\rm J}\end{aligned}[/tex].

Divide [tex]2.551 \times 10^{5}\; {\rm J}[/tex] by [tex]784\; {\rm J}[/tex] to find the number of times this weight could be lifted up within that energy budget:

[tex]\begin{aligned} \frac{2.551 \times 10^{5}\; {\rm J}}{784\; {\rm J}} &\approx 325 \end{aligned}[/tex].

Increasing the efficiency (the denominator) would reduce the amount of energy input required to achieve the same amount of useful work. Thus, the same energy budget would allow this weight to be lifted up for more times.

Answer:

D

Explanation:

Mass is the amount of matter your body has ....does not change on the Moon.

there is less gravity .....so your WEIGHT would decrease

Answer:

2.5 grams

Explanation:

p = mv

m = p/v

m = 0.0332 / 13.3

m = 0.0025kg

0.0025 x 1000 = 2.5

m = 2.5g

Answer:

Explanation:

The amplitude is extraneous information for this question.

Period (T) is simply a measure of time (how long it takes to complete a full cycle).

The frequency (f), is the reciprocal (how many cycles it can complete per unit of time).

The frequency reported is 12Hz.  Hz is a unit meaning "cycles per second"

Thus 12cycles = 1second.

To find the number of seconds per cycle, simply create the other unit fraction and simplify:

[tex]T=\frac{1second}{12cycles}\\T=0.8\bar{3}\frac{seconds}{cycle}\\[/tex]

[tex]T=0.83seconds[/tex]

The height of stairs a 60 kg student would have to run in order to burn off 1 Calorie of food energy will be 7.1 meters.

The potential energy is due to the virtue of the position and the height. The unit for the potential energy is the joule.

Given data;

Mass of student,m = 60 kg

Energy,E = 4190 J

Height of stairs,h=?

The potential energy is mainly dependent upon the height of the object. The potential energy is found as;

Potential energy = mgh

E=mgh

h=E/mg

h= 4190 J / (60 kg× 9.81  m/s²)

h = 7.1 metre

Hence the height of the stairs will be 7.1 meters.

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