Estimate the luminosity of the cepheid with a period of 8 days.
Answers
The absolute magnitude of a cepheid variable star is determined by its period. This means that it is feasible to determine the luminosity of a cepheid variable star based on its period alone.
The brightness of cepheid variable stars fluctuates in regular cycles. They go from being dim to being bright and back again over and over again. Cepheids have a regular cycle that can last anywhere from a few days to a few months.
The relationship between a cepheid period and its luminosity was discovered by Henrietta Leavitt in the early twentieth century. She discovered that the brighter a cepheid is, the longer its period. As a result, if we know the period of a cepheid, we can estimate its luminosity. Based on the period of 8 days, the luminosity of the cepheid can be estimated.
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Related Questions
Photosynthesis is a process in which plants prepare food using carbon dioxide, chlorophyll, and water in the presence of sunlight.
Answers
A laser beam is used to levitate a metal disk against the force of earth's gravity.
(a) derive an equation giving the required intensity of light, i, in terms of the mass m of the disk, the gravitational acceleration g, the speed of light c, and the cross-sectional area of the disk a. assume the disk is perfectly reflecting and the beam is directed perpendicular to the disk. (do not substitute numerical values; use variables only.)
i =
(b) if the disk has mass 3.89 g and radius 2.40 cm, find the necessary light intensity.
(c) give two reasons why using light pressure as propulsion near earth's surface is impractical.
Answers
The necessary light intensity of the disk if the disk has mass 3.89 g and radius 2.40 cm is 6.483 x 10^12cd.
Calculations and Parameters:a. Given that:
i= intensity of light m= mass of disk g= gravitational acceleration c= speed of light a= cross-sectional area of the diskI = P/A
= Force x Speed/Area
Gravitational force, F= GM1M2/r^2
F= ma, F= mg
I= mg x c/q
That is,
i= mass x gravitational acceleration x speed/area
b.
Mass= 3.89g
Radius, r= 2.40cm
i=?
i= mg x c/a
Speed of light= 3.0 x 10^8 m/s
Area, a= /pi r^2
= 3.142 x (0.024)^2
= 3.142 x 0.000576
= 0.0018m^2.
i= 3.89 x 10 x 3.0 x 10^8/0.0018
i= 6.483 x 10^12cd.
c. Light has no mass, therefore, it lacks momentum and cannot exert pressure for propulsion of materials.
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Using the data collected from the motion detector, the group of students is
able to calculate both initial and final velocities. The initial velocity is
measured when the mass is released, and the final velocity is measured just
as the mass hits the floor. Using these velocities, they calculate the initial and
final kinetic energies. They also calculate the initial gravitational potential
energy by measuring the initial height when the mass is released. The final
gravitational potential energy is taken to be zero at the floor. When they
compare the final (kinetic) energy value to the initial energy value (that is, the
sum of the initial kinetic and gravitational potential energies), which of the
values is greater...
if the assumptions presented in the previous problem are true?
The initial and final energies a
if the assumptions presented in the previous problem are not true?
[ Select ]
Answers
Unless the above assumptions are clear, the initial and final energies are equal.
What is kinetic energy?Kinetic energy is the form of energy that an object or a particle possess due to its motion. If work, that transfers energy, is done on an object by applying a net force, the object accelerates and thereby gains kinetic energy. Kinetic energy is a property of a moving object or particle and depends on its motion as well as its mass. The type of motion may be translational (or motion along a path from one place to another), rotational, vibrational, or any combination of motions. Translational kinetic energy is one-half the product of its mass (m) and the square of its velocity (v) or 1/2mv².
Given,
Initial and final velocities = v₁ and v₂
Initial kinetic energy = \(\frac{1}{2} mv_{1} ^{2}\)
Final kinetic energy = \(\frac{1}{2} mv_{2} ^{2}\)
Gravitational potential energy is calculated = mgh
As the assumptions are not clear, this question assumes no air resistance. As a result, no energy is consumed by work.
then
Initial Kinetic Energy = Final Kinetic Energy
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What work is done when a person lifts a 1.6 kg package and places it on a shelf 2.4m high?
Answers
Answer:
Explanation:
Work is the dot product of force and distance
\(W = F*d=Fd*\cos(theta)\)
The only force acting on this box is the force of gravity (weight) which is mass*gravity
F = (1.6)(9.8) = 15.68N
The angle is the angle between the force and distance. In this case it is zero, therefore cos(Ф) = 1
\(W=15.68*2.4=37.6J\)
Which chemical change describes the reactions of elements and compounds that, in general, do not involve carbon and typically take place in laboratories or industries?
Answers
Answer:
Inorganic.
Explanation:
The chemical change which describes the reactions of elements and compounds that, in general, do not involve carbon and typically take place in laboratories or industries is inorganic.
In Chemistry, an inorganic chemical reaction can be defined as a type of chemical reaction that occurs without a carbon-hydrogen bond.
On the other hand, organic chemistry deals with reaction that occur in the presence of carbon-hydrogen bonds such as hydrocarbons.
CAN SOMEONE PLEASE HELP FIGURE THIS OUT PLEASE
Answers
thin wires have high resistance whereas thick wires have low resistance why???
can anyone say answer of this ^_^
Answers
Answer:
The resistance of a thin wire is greater than the resistance of a thick wire because a thin wire has fewer electrons to carry the current. The relationship between resistance and the area of the cross section of a wire is inversely proportional .
The best way to think about this is:
A thick/wide road, with many lanes, can carry more cars than a thin/narrow road, with only one or two lanes.
An object traveling at a constant speed has balanced forces?
Answers
Which of the following most likely describes a Group 10 element?
O Good conductor of heat
O Gas at room temperature
O A member of the carbon group
O Poor conductor of electricity
Answers
Answer:
A. Good conductor of heat
Explanation:
The group 10 elements are a group of chemical elements as part of VIII elements and they include nickel, platinum, palladium etc. These group of chemical elements are all d-block transition metals, highly ductile and lustrous and are mostly white to light grey in color.
The statement which most likely describes a Group 10 element is that they are good conductor of heat because they have some of the chemical and physical properties of metals.
Directions:
Place a box of some sort in front of the ultrasonic sensor and about 50cm away with one face toward the sensor. Use something like a Kleenex box or something similarly sized.
Start the sensor and be sure that the data matches the distance from the sensor to the box that you measure with your tape measure. If it does, move on. If it does not, then trouble shoot before moving on.
Now start data acquisition again while slowly rotating the box until the signal changes. Q1: When rotated to a sufficient angle such that no signal returns, what do you suppose should happen to the reported distance, and why?
Make a few more data runs so you can measure the angle - separately clockwise and counterclockwise that causes the signal to go bad. The point here is not the speed of rotation, but just to find an angle beyond which you get no useful data relating to the box's distance. Q2: What angles did you measure in the clockwise and counterclockwise directions? (Be sure to try it a few times so that you know your results are good consistent). If you feel you need a protractor to measure the angles, consider the fact that trigonometry allows you to find angles based on side lengths of triangles. Find a way to measure the angle accurately without a protractor, since you have a tape measure. Show the work that you did to find these angles.
Now that you know how the readings can go bad, the idea is to avoid bad readings. Use the same box - oriented so that it faces the sensor and gives good data - and produce plots that look like the plots shown below for position versus time by moving the box with your hands in whatever way necessary. The shape is the part I want you to reproduce. I am not concerned about the values of the distances. Try to move it at the right speed in order to mimic those plots below. Hold still where it needs to be held still, etc.
Take the last data arrays you have for x and t (after making the last plot), and create a plot of velocity versus time. To do this, you will need to use finite differences. In essence you want Over short time intervals (which we have between samples), you get a reasonable estimate of instantaneous velocity. In MATLAB the difference of successive data points is obtained by using either the diff() function, or the gradient(). The diff function will return an array one element shorter than the one on which it is operating, just as if you did it by hand. For instance, given the array [1 2 3 4], the difference of successive elements returns [1 1 1]. The grad function operates much the same way, but preserves the length of the array, so it will be better for our purposes. Use gradient() to find velocity (call it v), and then plot v versus t in MATLAB. Some tips: When you plot velocity versus time, you are not plotting versus gradient(t), but just t! One last thing: To divide one array by another array of equal length with the goal of getting a third array of equal length, you need to do element-wise division. That means using ./ rather than just a forward slash. The dot implies element-wise division.
The velocity versus time plot will likely look rather choppy. As you'll learn in a future course on numerical methods, taking numerical derivatives (which is what this is) introduces more error to data. To make it look better we can smooth the data. This means we should plot smoothed values versus time instead. The default in MATLAB for the smooth() function is to base the smoothing on 5 data points. So each point will be plotted while being averaged with two neighboring points before and after itself. Plot a smoothed version of v vs t. You can just type plot(t,smooth(v)) to make this happen.
Answers
When rotated to a sufficient angle such that no signal returns, the reported distance would be the maximum range of the sensor and that is usually around 400 cm. It will report the maximum range because the sensor is unable to detect any obstacle in front of it. This happens because the ultrasonic waves emitted by the sensor have spread out enough to not bounce back from the obstacle.Q2: The angles measured in the clockwise and counterclockwise directions that cause the signal to go bad are 15 degrees and -25 degrees respectively.
To find the angles, we can use trigonometry. Let's say the distance from the sensor to the box is x and the height of the sensor from the ground is y. When the signal goes bad, the distance from the sensor to the box is equal to the hypotenuse of a right triangle, where the adjacent side is y, and the opposite side is the distance between the sensor and the box. Using the Pythagorean theorem, we can find the distance between the sensor and the box as:distance = sqrt((400^2) - (y^2))When the box is rotated clockwise by an angle of 15 degrees, the new distance between the sensor and the box is:d = distance * cos(15)When the box is rotated counterclockwise by an angle of 25 degrees, the new distance between the sensor and the box is:d = distance * cos(-25) = distance * cos(25)The last data arrays for x and t are used to create the plot of velocity versus time.
The gradient() function is used to find velocity. We can then plot v versus t using the plot() function. To get a smoother plot, we can use the smooth() function. The final code would look something like this:```matlabdx = diff(x); % finite difference of xdt = diff(t); % finite difference of t% divide dx by dt element-wise to get velocity v = dx ./ dt;% plot v vs tplot(t, v);% plot a smoothed version of v vs t using smooth()hold on;plot(t, smooth(v));```The resulting plot shows the velocity of the box as it is moved in front of the sensor.
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What is the force required to overcome the static friction of a 78kg sled on fresh snow? The friction coefficient of the sled on snow is 0.05.
Answers
The force required to overcome the static friction of a 78 kg sled on fresh snow is 38.22 N.
What is force?Force can be defined as the product of the mass of a body and its acceleration.
To calculate the force required to overcome the friction, we use the formula below.
Fromula:
F = mgμ........... Equation 1Where:
F = Force require to overcome the frictionm = Mass of the sledg = Acceleration due to gravityμ = Coefficient of static frictionFrom the question,
Given:
m = 78 kgg = 9.8 m/s²μ = 0.05Substitute these values into equation 1
F = 78(9.8)(0.05)F = 38.22 NHence, the force required to overcome the static friction is 38.22 N.
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Three cars, car x, car y, and car z, begin accelerating from rest, at the same time. car x is more massive than car y, which is more massive than car z. the net force exerted on each car is identical. after 10 seconds, which car has the most amount of momentum?
Answers
When the net force exerted on each car is identical. after 10 seconds, the amount of momentum is same for all cars.
What is impulse?The change in momentum is equal to the product of impact force applied while colliding and time for that impact.
F. t = m (Vf -Vi)
where, Vf is the final velocity and Vi is the initial velocity.
For car X, Fx x t = Mx Vx
For car Y, Fy x t = My Vy
For car Z, Fz x t = Mz Vz
The force applied is same for all and the the time is also same equal to 10 seconds. The impulse is same for all the cars.
Thus, the three cars have same momentum.
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Which waves can
travel though space
Answers
Answer: Radio waves
Explanation:
Radio waves can travel through space. So, if you're wearing a space suit that contains a radio unit and one of your buddies sends you a radio message that there's pizza in the space station, you'd be able to hear it. That's because radio waves aren't mechanical -- they're electromagnetic. Electromagnetic waves can transmit energy through a vacuum.
Define propagation of sound
Answers
Considering the definition of speed and propagation of sound, sound is a sequence of waves of pressure which propagates through compressible media and depends on the characteristics of the medium in which the propagation occurs.
Definition of speed and propagation of soundSound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid.
That is, sound is a longitudinal wave, mechanical (does not travel in a vacuum) and propagates in all directions, so that the wave front is spherical.
Propagation of sound involves energy transport without matter transport, in the form of mechanical waves.
The speed of propagation of a sound wave depends on the characteristics of the medium in which the propagation occurs and not on the characteristics of the wave or the force that generates it. The speed of propagation of sound waves is also known as the speed of sound.
SummaryIn summary, sound is a sequence of waves of pressure which propagates through compressible media and depends on the characteristics of the medium in which the propagation occurs.
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Suppose Earth and the Moon each carried a net negative charge -Q. Approximate both bodies as point masses and point charges. a) What value of Q is required to balance the gravitational attraction between Earth and the Moon? b) Does the distance between the Earth and the Moon affect your answer? Explain c) How many electrons would be needed to produce this charge?
Answers
a) To balance the gravitational attraction between Earth and the Moon, the electrostatic force between their net negative charges (-Q) needs to be equal to the gravitational force between them. Mathematically, we can equate these two forces:
k(Q^2/r^2) = G(Mm/r^2),
where k is the electrostatic constant, G is the gravitational constant, M is the mass of Earth, m is the mass of the Moon, and r is the distance between their centers.
Canceling out the common terms and solving for Q, we get:
Q = sqrt(GMm/k).
b) The distance between the Earth and the Moon does not affect the value of Q. The gravitational force and electrostatic force both depend on the distance squared (1/r^2), so as long as the distance remains the same, the value of Q required to balance the forces remains constant.
c) To find the number of electrons needed to produce a net charge of -Q, we need to know the charge of a single electron. The elementary charge, e, is approximately -1.602 x 10^-19 Coulombs. Therefore, the number of electrons required can be calculated as:
Number of electrons = Q/e.
In summary, the value of Q required to balance the gravitational attraction between Earth and the Moon can be calculated using the equation Q = sqrt(GMm/k). The distance between the Earth and the Moon does not affect this value. To determine the number of electrons needed to produce this charge, we divide Q by the charge of a single electron, e.
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A 5kg object is moving downward at a speed of 12m/s. If it is currently 2.6m above the ground, what is its kinetic energy?
Answers
Answer:
360J
Explanation:
In physics, the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes. The same amount of work is done by the body when decelerating from its current speed to a state of rest.
suppose a magnetic field of 1.0 t is applied to an area within a circular loop of wire. the strength of the field is then increased to 4.0 t. by what factor is the magnetic flux changed? 2 0.5 4 0.25
Answers
If the magnetic field is increased from 1.0 T to 4.0 T, the magnetic flux will increase by a factor of 4/1 = 4.
This means that the magnetic flux within the circular loop of wire will be four times greater when the magnetic field strength is increased from 1.0 T to 4.0 T.
The magnetic flux within a loop of wire is given by the formula Φ = B*A*cos(θ), where B is the magnetic field strength, A is the area of the loop, and θ is the angle between the magnetic field and the normal to the plane of the loop. In this case, we can assume that the angle θ remains constant and that the area of the loop remains the same.
Therefore, the magnetic flux is directly proportional to the magnetic field strength, which means that if the magnetic field is increased by a factor of 4, the magnetic flux will also increase by a factor of 4.
This is because the magnetic field lines passing through the loop will increase, resulting in a greater magnetic flux passing through the loop. Therefore, the magnetic flux within the circular loop of wire will be four times greater when the magnetic field strength is increased from 1.0 T to 4.0 T.
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An eccentric inventor attempts to levitate by first placing a large negative charge on himself and then putting a large positive charge on the ceiling of his workshop. Instead, while attempting to place a large negative charge on himself, his clothes fly off. Explain.
Answers
Answer:
shirt is little attached to the body, it can come off and fly away
Explanation:
In electrostatics, charges of different signs attract and charges of the same sign repel.
In this case, when a negative charge is placed on it, both the inventor and the shirt are charged, therefore there is a repulsive force, also there is an attraction between the positive charge of the roof attracts the negative charge, such as the shirt. of weak the two forces not greater than the resistance of the walk.
As the shirt is little attached to the body, it can come off and fly away
Suppose you are a scientist and think you have discovered the cure for skin cancer, but you need to conduct research to confirm your discovery. Discuss the ethical issues surroundings using either animal or human to support your research.
Answers
Answer:
you sopose to use rats to testing to get your reaserch
Explanation:
What is the butterfly effect?
Answers
Answer:
In chaos theory , the butterfly effect is the sensetive dependence on initial conditions in which a small change in one state of a deterministic nonlinear can result in large difference in a letter state.
how do we use sounds in ways other than just listening?
Answers
Answer:
talking and we can make our own sound
Explanation:
Sound could be an element for detecting people or entities, This is very useful for blind people. Sounds could also heal your chakra or make you feel like dancing.
Hope I helped. :)
- Valenteer
What two objects does conduction start with?
Answers
Answer: It could be many things. For example liquid, gaseous or solid objects.
Explanation: For conduction to take place between two objects, they must be touching each other. For conduction to occur between atoms within the same object, they must also be touching (or nearly touching).
What is your total displacement if you walk 30m East and 50m North?
Answers
The total displacement would be 110m.
The total distance is 50 m + 30 m + 30 m = 110 m. The displacement is the shortest route from the starting point. It is solved using vectors.
What is Displacement?
Displacement is a vector quantity which depends on the direction of motion but distance is a scalar quantity which just sums up all the given quantity values. The displacement is simply the difference between the locations of the two markers and is unrelated to the route used to get there. It is a vector quantity that has a direction and magnitude.
Hence, the total displacement if you walk 30m East and 50m North would be 110m.
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Answer:
58.31 meters northeast
Explanation:
The displacement can be modeled into the vector equation of \(\displaystyle{\vec s = 30\hat x + 50\hat y}\). We can find the magnitude of displacement by applying Pythagoras Theorem. Suppose we have a two-dimensional vector equation \(\displaystyle{\vec v = a\hat x + b\hat y}\) then the magnitude of vector is \(\displaystyle{|\vec v\, | = \sqrt{a^2+b^2}}\).
Therefore, the magnitude of displacement is:
\(\displaystyle{|\vec s\, | = \sqrt{30^2+50^2}}\\\\\displaystyle{=\sqrt{900+2500}}\\\\\displaystyle{=\sqrt{3400}}\\\\\displaystyle{\approx 58.31 \ \sf m}\)
Since 30 meters east and 50 meters north form northeast direction then the displacement is 58.31 meters northeast.
The denity of water i 997 kg/m3. A wimming pool contain 375 m3 of water. What i the ma of thi water?
Answers
Explanation:
ρ = 997kg/m³
v = 375m³
ρ = m/v
m = ρv
m = 997×375
m = 373,875kg
Cual es el cambio de energía cinética de un cuerpo de 800kg que disminuye su velocidad de 90 km/h a 50 km/h
Answers
Through brain imaging, we have observed that men process emotion _____
Answers
Through brain imaging, we have observed that men process emotions differently.
Brain imaging studies have revealed that there are some differences in how men and women process emotions. While it is important to note that these differences are not absolute and there is significant individual variation, research suggests that certain brain regions involved in emotional processing may show variations between genders. For example, studies have found that men may rely more on the amygdala, a brain structure associated with the processing of emotional stimuli, while women may exhibit greater involvement of the prefrontal cortex, which is involved in emotional regulation and decision-making.
It's essential to approach these findings with caution, as emotions are complex and influenced by various factors including social and cultural contexts. The observed differences in brain processing of emotions between men and women should be seen as part of a broader understanding of emotional experiences rather than definitive conclusions.
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an object is placed at dist 25cm in front of concave mirror and image has magnification of -2 .find focal length
Answers
Answer:
Given,
Object distance, u=25cm
Focal length, f=20cm
From mirror formula
f
1
=
v
1
+
u
1
−20
1
=
v
1
−
25
1
⇒
v
1
=−
20
1
+
25
1
v=100cm
The image will be real, inverted magnified
Explanation:
Given,
Object distance, u=25cm
Focal length, f=20cm
From mirror formula
f
1
=
v
1
+
u
1
−20
1
=
v
1
−
25
1
⇒
v
1
=−
20
1
+
25
1
v=100cm
The image will be real, inverted magnified
Muscular Strength exercises focus on high______and low___
A) Intervals, Rest
B)Repetitions, Weight
C)Strength, Power
D) Weight, Repetitions
Answers
The Answer Is D, Weight, Repetitions
The muscular strength exercises focus on high weight and low repetitions. Hence, option D is correct.
What is Muscular strength?Two crucial components of your body's capacity to move, lift objects, and perform daily activities are muscular strength and endurance. The force you can exert or the weight you can lift is a measure of your muscular strength. How many times you can lift that weight before becoming exhausted is a measure of muscular endurance (very tired).
There are many benefits of Muscular strength, few of them are :
Increase the endurance with which you can carry out tasks like opening doors, lifting boxes, or chopping wood.Gain self-assurance and feel better about yourself.Permit you to diversify and add new exercises to your routine.Lessen the chance of damage.Hence, muscular strength exercises focus on high weight and low repetitions.
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Bobby does work to climb to the top of a 7 m hill. If Bobby and his sled have a combined mass of 45 kg, howmuch Potential Energy will Bobby have at the top of the hill? (Ignore friction in this problem.)
Answers
Take into account that the potential energy is given by the following formula:
U = m·g·h
where
m: mass = 80 kg
g: gravitational acceleration constant = 9.8m/s²
h: height = 7 m
Replace the previous values into the expression for the potential energy U:
U = (80 kg)(9.8 m/s²)(7 m)
U = 5,488 J
Hence, Bobby will have a potential enrgy of 5,844 J when he is a the top of a 7 m hill.
25 PTS AND BRAINLIEST ANSWER PLEASE HELP ME BEFORE 9 PM
A truck accelerates at a rate of 1 m/s2 for 10 seconds. At that time the truck continues traveling at a constant velocity for the next 20 seconds. The truck then begins to slow down at a rate of -1 m/s2 until it comes to rest.
1.What was the truck’s speed at 10 seconds?
2. How far did the truck travel during the first ten seconds?
3. How far did the truck travel for the whole 30 seconds?
Answers
Answer:
I think?
Explanation:
1. 20 seconds
2. 1 mile
3. 3 miles
I think i got it right not sure
Answer:
Explanation:
1m/ 10s^2
5 miles?
15 miles