Answer:
B. The dentist uses X-ray radiography, which takes too short a time to cause those problems.
Explanation:
The statement B would best inform Sally of the level of risk. The dentist uses X-ray radiography, which takes too short a time to cause those problems and risk.
What is X-ray imaging?X-ray imaging provides images of human internal organs. The photos depict your body parts in various colors of black and white.
Because various tissues absorb varying quantities of radiation, this is the case. Because calcium absorbs the most x-rays, bones appear white.
When X-ray radiation passes into our bodies, it damages molecular structures and may cause injury.
Human cells are damaged by extremely high doses of radiation, as indicated by skin burns, hair loss, and an increased risk of cancer.
Sally is concerned about the X-ray images her dentist plans to take of her teeth. She has read that X-rays can cause tissue effects, such as skin reddening and hair loss.
The statement B would best inform Sally about the level of risk. The dentist uses X-ray radiography, which takes too short a time to cause those problems and risk.
Hence, statement B would best inform Sally about the level of risk.
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A uniform string of length 10.0 m and weight 0.32 N is attached to the ceiling. A weight of 1.00 kN hangs from its lower end. The lower end of the string is suddenly displaced horizontally. How long does it take the resulting wave pulse to travel to the upper end
Answer: 0.0180701 s
Explanation:
Given the following :
Length of string (L) = 10 m
Weight of string (W) = 0.32 N
Weight attached to lower end = 1kN = 1×10^3
Using the relation:
Time (t) = √ (weight of string * Length) / weight attached to lower end * acceleration due to gravity
g = acceleration due to gravity = 9.8m/s^2
Weight of string = 0.32N
Time(t) = √ (0.32 * 10) / [(1*10^3) * (9.8)]
Time = √3.2 / 9800
= √0.0003265
= 0.0180701s
How does increasing frequency affect the crests of a wave?
They get higher.
They get closer together.
They get lower.
They get farther apart.
Answer:
they get closer together
Explanation:
The large-scale distribution of galaxies in the universe reveals Group of answer choices a smooth, continuous, and homogenous arrangement of clusters large voids, with most of the galaxies lying in filaments and sheets a large supercluster at the center of universe a central void with walls of galaxies at the edge of the universe
Question
The large-scale distribution of galaxies in the universe reveals
A) a smooth, continuous, and homogenous arrangement of clusters
B) large voids, with most of the galaxies lying in filaments and sheets a large supercluster at the center of the universe
C) a central void with walls of galaxies at the edge of the universe
Group of answer choices
Answer:
The correct answer is B)
Explanation:
The universe is arranged in a filamentary structure. Filamentary structures are very large. They are the largest kind of structures in the universe and comprise mostly of galaxies that are held together by gravity.
The structures found within Galaxy filaments have thread-like qualities spanning 52 to 78.7 megaparsecs h⁻¹ in lenght.
Other phenomena associated with the nature fo the universe is the existence of void spaces.
Cheers!
By starting with a falsifiable hypothesis and proceeding to gather data and ensure replicability, a scientist can contribute to the potential formation of a(n)
Answer:
theory
Explanation:
A scientist can contribute to the formation of a theory in a particular subject by conducting research along the line of that subject.
Conducting research requires the formation of a hypothesis and testing the hypothesis by conducting a relevant experiment during which data are gathered, analyzed, and interpreted in order to falsify or accept the hypothesis.
A good experiment must be replicate-able. When the same experiment is repeated by different independent researchers and the same conclusion is arrived at, this could potentially lead to the formation of a theory.
Hence, a scientist can contribute to the formation of a theory by conducting an experiment with replicability in order to test a hypothesis.
Can someone please help me?
An alien spaceship is 650 m above the ground and moving at a constant velocity of 175 m/s upwards.
How high above the ground is the ship after 5 seconds?
Answer:
1525 meters above ground
Explanation:
So to do this you will need to write this in slope intercept form or [tex]y=mx+b[/tex]. So 650 would be the b, 175 would be the m, and the x would be 5 so the equation would be [tex]y=175(5)+650[/tex] so if you solve or simplify the equation you will get 1525 meters above the ground and that would be our final answer.
Which is the best example of muscular endurance
Answer:
personally I'd say C by do not know if that is the exact answer
Two charged objects are separated by some distance. The charge on the first object is greater than the charge on the second object. How do the forces that the two objects exert on each other compare
Even though the charge on the first object is greater, the forces that the two objects exert on each other are equal
Ozone molecules in the stratosphere absorb much of the harmful radiation from the sun. How many ozone molecules are present in 2.00 L of air under the stratospheric ozone conditions of 275 K temperature and 1.89 × 10−3 atm pressure?
Answer:
1.01×10^20 molecules of ozone.
Explanation:
Data obtained from the question include:
Volume (V) = 2 L
Temperature (T) = 275 K
Pressure (P) = 1.89×10¯³ atm
Gas constant (R) = 0.0821 atm.L/Kmol
Number of mole (n) of ozone =.?
Using the ideal gas equation, we can obtain the number of mole of ozone as follow:
PV = nRT
1.89×10¯³ x 2 = n x 0.0821 x 275
Divide both side by 0.0821 x 275
n = (1.89×10¯³ x 2) /(0.0821 x 275)
n = 1.67×10¯⁴ mole.
Therefore the number of mole of ozone in 2 L of air is 1.67×10¯⁴ mole.
Finally, we shall determine the number of molecules present in 1.67×10¯⁴ mole of ozone.
This can be obtained as follow:
From Avogadro's hypothesis, 1 mole of any substance contains 6.02×10²³ molecules. This implies that 1 mole of ozone contains 6.02×10²³ molecules.
If 1 mole of ozone contains 6.02×10²³ molecules,
therefore, 1.67×10¯⁴ mole of ozone will contain = 1.67×10¯⁴ x 6.02×10²³ = 1.01×10^20 molecules.
Therefore, 1.01×10^20 molecules of ozone are present in 2 L of air.
This is a form of energy representing the motion of the molecules which make up an object. A. Thermal Energy B. Kinetic Energy C. Gravitational Potential Energy D. Chemical Potential Energy
Answer:
Kinetic energy.
Explanation:
There are many kinds of energy. Some of them are kinetic energy, potential energy, thermal energy etc. The energy that shows the motion of the object is called its kinetic energy.Also, the sum of kinetic energy and the gravitational potential energy is called mechanical energy. Out of the given options, kinetic energy is the form of energy that represents the motion of the molecules which make up an object. Hence, the correct option is (B).a skydiver jumped out of a plane and fell 9 miles to the ground. his average speed while falling was 174 miles/hour. how much time did the dive last?
Answer:
t = 0.051 seconds
Explanation:
Given that,
A skydiver jumped out of a plane and fell 9 miles to the ground. It means 9 miles is the distance covered.
The average speed of the skydiver is 174 miles/hour
We need to find the time for which he dive last. It means t is the time taken. Total distance covered divided by time taken is called average speed. So,
[tex]v=\dfrac{d}{t}\\\\t=\dfrac{d}{v}\\\\t=\dfrac{9}{174}\\\\t=0.051\ s[/tex]
So, a skydiver dive for 0.051 seconds.
Bumper car A (281 kg) moving +2.82 m/s makes an elastic collision with bumper car B (209 kg) moving +1.72 m/s. What is the velocity of car B after the collision?
The velocity of car B after the calculation can be obtained as 5.5 m/s.
What is a collision?We have to look at the principle of the conservation of the linear momentum and that is what we need so as to be able to deal with the problem that we have in this question as we have it here.
We know that the total momentum of the system would have to be constant and the implication of this is that the momentum before collision must be the same as the momentum after collision if we have been able to designate the system as a closed system.
Using the formula as we have shown it, we know that;
Momentum before Collison must be equal to momentum after collision
As such we have the following as shown below;
(281 * 2.82) + (209 * 1.72) = (281 * 0) + (209 * v)
792.42 + 359.48 = 209 v
v = 5.5 m/s
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1. Analogies exist between rotational and translational physical quantities. Identify the rotational term analogous to each of the following: acceleration, force, mass, work, translational kinetic energy, linear momentum, impulse.
2. Explain why centripetal acceleration changes the direction of velocity in circular motion but not its magnitude.
Answer:
1) a α, m I, W=F.d W =τ . θ,
2) a = v²/r
Explanation:
1) The amounts of rotational and translational motion are related
acceleration is
a = d²x / dt²
linear displacement is equivalent to angular rotation, therefore angular acceleration is
α = d²θ / dt²
force in linear motion is equivalent to moment in endowment motion
F = m a
τ = I α
the mass is the inertia of the translation, in rotational motion the moment of inertia is the rotational inertia
I = m r²
Work is defined by W = F. d
in rotation it is defined by W = τ . θ
The linear momentum is p = mv
the angular momentum L = I w
momentum the linear motion is I = F dt
in the rotation it is I = τ dt
2) The velocity is a vector therefore it has modulus and direction, linear acceleration changes the modulus of velocity, whereas circular motion changes the direction (the other element of the vector).
[tex]a_{c}[/tex]Ac = v²/r
Which reverses the flow of current through
an electric motor?
Answer:
a commutator
Explanation:
Calculating heat gained, need help!!!
Q=(m)(c)(triangle T)
trial 1:
Q=(0.4)(4.186 J/kg)(78)=?
trial 2:
Q=(0.6)(4.186 J/kg)(78)=?
trial 3:
Q=(0.45)(4.186 J/kg)(75)=?
Explanation:
q = mCΔT
where m is mass,
C is specific heat capacity,
and ΔT is change in temperature.
Make sure all your units match. Assuming the substance is water, C = 4186 J/kg/°C.
Trial 1:
q = (0.4 kg) (4186 J/kg/°C) (78°C)
q = 130,600 J
Trial 2:
q = (0.6 kg) (4186 J/kg/°C) (78°C)
q = 195,900 J
Trial 3:
q = (0.45 kg) (4186 J/kg/°C) (75°C)
q = 141,300 J
A 140-Hz sound travels through pure carbon dioxide. The wavelength of the sound is measured to be 1.92 m. What is the speed of sound in carbon dioxide?
Answer:
V = 268.8 m/s
Explanation:
The speed of a wave in general is given by the following formula:
V = fλ
where,
V = Speed of that wave
f = Frequency of the wave
λ = wavelength of the wave
In this case we have a sound wave, travelling across carbon dioxide. The properties of sound wave are as follows:
V = Speed of Sound in Carbon dioxide = ?
f = frequency of sound wave = 140 Hz
λ = wavelength of sound wave = 1.92 m
Therefore,
V = (140 Hz)(1.92 m)
V = 268.8 m/s
On a horizontal frictionless surface a mass M is attached to two light elastic strings both having length l and both made of the same material. The mass is displaced by a small displacement Δy such that equal tensions T exist in the two strings, as shown in the figure. The mass is released and begins to oscillate back and forth. Assume that the displacement is small enough so that the tensions do not change appreciably. (a) Show that the restoring force on the mass can be given by F = -(2T∆y)/l (for small angles) (b) Derive an expression for the frequency of oscillation.
Answer:
(a) By small angle approximation, we have;
F = -2×T×Δy/l
(b) [tex]The \ frequency \ of \ oscillation, \ f = \dfrac{1}{2\cdot \pi }\cdot\sqrt{\dfrac{2 \cdot T}{l \cdot M} }[/tex]
Explanation:
(a) The diagram shows the mass, M, being restored by two equal tension, T acting on the elastic strings l, such the restoring force, F acts along the path of motion of the mass, with distance Δy
Therefore, the component of the tension T that form part of the restoring force is given as follows;
Let the angle between the line representing the extension of the elastic strings T and the initial position of the string = ∅
Then we have;
String force, [tex]F_{string}[/tex] = T×sin∅ + T×cos∅ + T×sin∅ - T×cos∅ = 2×T×sin∅
Whereby the angle is small, we have;
sin∅ ≈ tan∅ = Δy/l
Which gives;
[tex]F_{string}[/tex] = 2×T×sin∅ = 2×T×Δy/l (for small angles)
Restoring force F = [tex]-F_{string}[/tex] = -2×T×Δy/l
F = -2×T×Δy/l
(b) Given that the the tensions do not change appreciably as the mass, M, oscillates from Δy we have;
By Hooke's law, F = -k×x
Whereby Δy corresponds to the maximum displacement of the mass, M from the rest position, which gives;
Which gives;
F = M×a = -k×Δy
a = -k×Δy/M
d²(Δy)/dt² = -k×Δy/M
When we put angular frequency as follows;
ω² = k/M
We get;
d²(Δy)/dt² = -ω²×Δy
Which gives;
Δy(t) = A×cos(ωt + Ф)
The angular frequency is thus, ω = √(k/M)
Period of oscillation = 2·π/ω = 2·π/√(k/M)
The frequency of oscillation, f = 1/T = √(k/M)/(2·π)
Where:
k = 2·T/l, we have;
f = √(k/M)/(2·π) = √(2·T/l)/m)/(2·π)
The frequency of oscillation is given as follows;
[tex]f = \dfrac{1}{2\cdot \pi }\cdot\sqrt{\dfrac{2 \cdot T}{l \cdot M} }[/tex]
an attempt to estimate the height of a tree the Shadow of an upright metre rule was found to be 25 cm and the length of the Shadow of the tree was 7 m what is the height of the tree
Answer:
The actual height of the tree is 28 m
Explanation:
The given information are;
The length of the shadow of an upright meter rule = 25 cm
The actual height of the meter rule = 100 cm
The length of the shadow of the tree = 7 m
The actual height of the tree = h
We have
[tex]\dfrac{The \ length \ of \ the \ shadow \ of \ an \ upright \ metre \ rule}{The \ actual \ height \ of \ the \ metre \ rule} = \dfrac{The \ length \ of \ the \ shadow \ of \ the \ tree}{The \ actual \ height \ of \ the \ tree}[/tex]Which gives;
[tex]\dfrac{25 \ cm}{100 \ cm} = \dfrac{7 \ m}{The \ actual \ height \ of \ the \ tree}[/tex]
Therefore;
[tex]The \ actual \ height \ of \ the \ tree = 7 \ m \times \dfrac{100 \ cm}{25\ cm} = 7 \ m \times 4 = 28 \ m[/tex]
That is the actual height of the tree = 28 m.
Which of the following object is in dynamic equilibrium?
Answer:
A car driving in a straight line 20 m/s
Explanation:
ayepecks silly
What happens when white light shines through a translucent, red, glass window? a) All colors of light except red are transmitted through the glass. b) Red light is transmitted through and reflected by the glass c) Red light is absorbed by the glass d) all colors except red are reflected by the glass
Answer:
b. Red light is transmitted through and reflected by the glass
Explanation:
Give me brainliest plz!
All of the wavelengths of the red light are absorbed when it passes through a translucent red glass window, but the red light is transmitted and reflected.
What happens when white light shines through red glass?Red light emerges from the other side of a white light source that has been passed through a red filter. This is so that only red light can pass through the red filter. The spectrum's other colors (wavelengths) are absorbed. Similar to this, a green filter only lets through green light.White light is colorless light that contains all the wavelengths of the visible spectrum. Only specific wavelengths of white light are filtered through transparent or translucent things.Through a colorful glass, white light shines through. Except for the color it is shining through, all light wavelengths are absorbed by the glass.Therefore, if the red light passes through a translucent, red, glass, window, all the wavelengths are absorbed but the red light is transmitted and reflected.
Therefore, the correct answer is option b) Red light is transmitted through and reflected by the glass.
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Suppose a 50.0 g block of silver (specific heat = 0.2350 J/g·°C) at 100.°C is placed in contact with a 50.0 g block of iron (specific heat = 0.4494 J/g·°C) at 0.00°C, and the two blocks are insulated from the rest of the universe. The final temperature of the two blocks will be:
Answer:
34.34 °C
Explanation:
From the question,
Heat lost by the silver block = heat gained by the iron block.
cm(x-y) = c'm'(y-z)................... Equation 1
Where c = specific heat capacity of the silver block, m = mass of the silver block, c' = specific heat capacity of the iron, m' = mass of the iron. x = initial temperature of the silver block, z = initial temperature of the iron, y = final temperature of the mixture.
make y the subject of the equation
y = (cmx+c'm'z)/(cm+c'm')............... Equation 2
Given: c = 50 g, c = 0.2350 J/g·°C, x = 100°C, m' = 50 g, c' = 0.4494 J/g.°C, z = 0°C
Substitute these values into equation 2
y = [(50×0.2350×100)+(50×0.4494×0)]/[(50×0.2350)+(50+0.4494)]
y = 1175/(11.75+22.47)
y = 1175/34.22
y = 34.34 °C
Velocity is a description of an object’s blank
Velocity is the description of an object's motion from one point to another.
It tells the speed with which the trip is completed, and the direction from the start-point to the end-point. It tells nothing about any twists, turns, loops, bends, or stops along the way.
formula of minimmum pressure
Answer:
pressure=force/area
A carpenter measured the lengeth of a small piece of timber as 24.6cm .Calculate the relative error in the measurement if the true length is 24.5cm
ANSWER:
0.4081%
Explanation:
Difference=24.6-24.5=0.1
Relative error = 0.1/24.5*100=0.4081%
Relative error is equal to the = difference between both the values/The true value *100
Show that energy dissipated due to motion of a conductor in the magnetic field is due to mechanical energy.
Explanation:
let us use the explanation below to get the intuition so desired;
According to Faraday's law of electro magnetic induction, when ever a coil/conductor is made to rotate in a magnetic field, voltage or emf is created and current is produced, in the long run energy has be produced or converted.
The conversion of this energy is made possible by the motion of the coil/conductor is the magnetic field, just by the motion of the conductor cutting through the magnetic field, thus creating electro motive force(E.M.F) hence producing current, and ultimately energy is created
A small child has a wagon with a mass of 10 kilograms. The child pulls on the wagon with a force of 2 newtons. What is the acceleration of the wagon?
Answer:
0.2 m/s²Explanation:
Given,
Mass ( m ) = 10 kg
Force ( f ) = 2 Newtons
Acceleration ( a ) = ?
Now, let's find the acceleration :
We know that,
[tex]f = ma[/tex]
Plug the values
[tex]2 = 10a[/tex]
Swap the sides of the equation
[tex]10a = 2[/tex]
Divide both sides of the equation by 10
[tex] \frac{10a}{10} = \frac{2}{10} [/tex]
Calculate
[tex]a = 0.2 \: {metre \: per \: second \: }^{2} [/tex]
Hope this helps...
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(a) In electron-volts, how much work does an ideal battery with a 17.0 V emf do on an electron that passes through the battery from the positive to the negative terminal? (b) If 3.88 × 1018 electrons pass through each second, what is the power of the battery?
Answer:
(a) 17.0eV
(b) 10.55W
Explanation:
(a) The amount of work done (W) on an electron by an ideal battery of emf value of V as it moves from the positive to the negative terminal is given by;
W = q x V --------(i)
Where;
q = charge on the electron = 1e
From the question;
V = 17.0 V
Substitute the values of q and V into equation (i) as follows;
W = 1e x 17.0
W = 17.0eV
Therefore, the work done in electron volts is 17.0
(b) The power (P) of the battery as some electrons (n) pass through it at time t, is given as;
P = (n q V) / t --------------(ii)
Where;
n = number of electrons = 3.88 x 10¹⁸
t = 1s
q = 1.6 x 10⁻¹⁹C
V = 17.0V
Substitute these values into equation (ii) as follows;
P = (3.88 x 10¹⁸ x 1.6 x 10⁻¹⁹ x 17.0) / 1
P = 10.55W
Therefore the power of the battery is 10.55W
You and a friend are on a swing set and her swing is slightly longer than yours. If you both start swinging at the same time, from the same height, where will she be after you have completed one complete swing back and forth?
a. She will still be at the same height as you.
b. She will be slightly higher than you.
c. She will be slightly lower than you but moving downward away from you.
d. She will be slightly lower than you but moving upward toward you.
Answer:
d. She will be slightly lower than you but moving upward toward you.
Explanation:
Since your swing is slightly shorter than your friend's swing, then you will have more angular speed than your friend. Angular speed increases with a decrease in radius. The closer the body is to the center, the faster the body swings. By the time you would have completed one complete swing back and forth, your friend will just be moving towards you, and she will be slightly lower than you but moving upwards towards you. This principle is the same reason gymnasts pull their limbs closer to their body when they need to swing faster.
Which statement describes one feature of a closed circuit? Charges do not flow. Bulbs will not shine. The circuit is broken. The circuit is complete.
I inferred you've referring to a close electrical circuit.
Answer:
The circuit is complete.
Explanation:
A closed electrical circuit is indeed a complete circuit. Also, it allows charges to flow, the bulbs in the circuit will shine and it is not broken.
It is termed closed circuit because there is no brokage in the series of electrical wires or the switch; which may prevent the free flow of current or charges. Thus, a feature that marks closed circuits is that they are complete.
Answer:
The circuit is complete.
Explanation:
HELP me pleaseeee somebody
an object is placed 30cm from a mirror of focal length 15 cm the object is 7.5cm tall. where is the image located? how tall is the image??
Explanation:
It is given that,
Object distance from the mirror, u = -30 cm
Focal length of the mirror, f = +15 cm
Size of the object, h = 7.5 cm
We need to find the image distance and the size of the image.
Mirror's formula, [tex]\dfrac{1}{v}+\dfrac{1}{u}=\dfrac{1}{f}[/tex]
v is image distance
[tex]\dfrac{1}{v}=\dfrac{1}{f}-\dfrac{1}{u}\\\\\dfrac{1}{v}=\dfrac{1}{(15)}-\dfrac{1}{(-30)}\\\\v=10\ cm[/tex]
Let h' is the size of the image. So,
[tex]\dfrac{h'}{h}=\dfrac{-v}{u}\\\\h'=\dfrac{-vh}{u}\\\\h'=\dfrac{-10\times 7.5}{-30}\\\\h'=2.5\ cm[/tex]
So, the image is located at a distance of 10 cm and the size of the image is 2.5 cm.
We have seen that starlight passing through the interstellar medium is dimmed and reddened. Look at the photo of a sunset on Earth. The Sun’s light also appears reddish at sunset. Given your understanding of the reddening of starlight, why do you think sunsets appear red?
Answer:
Explanation:
Reddening of sun's rays at sunset and sunrise is due to scattering of light . The white light consisting of seven colours coming from the sun are scattered in different directions when they fall on the air particles present in atmosphere . Red coloured light scatters least and it travels straight forward to the viewer on the earth . On the other hand other colours scatter most and therefore they go out of area of vision for the viewer on the earth . Since only red colour reaches the eye of the viewer , sun's ray appear red . This happens during sunrise and sunset . It is so because during this period , sun rays travel far greater distance through atmosphere , so scattering is most pronounced .