According to the Big Bang theory, after the "bang," the universe remained dark until about 380,000 years later, when neutral atoms began to form.
During this period, the universe was filled with a hot, dense plasma of protons, electrons, and photons constantly interacting, which prevented light from traveling freely. This era is known as the "cosmic dark age." Around 380,000 years post-Big Bang, the universe cooled enough for protons and electrons to combine and form neutral hydrogen atoms, a process called "recombination."
This allowed photons to travel unimpeded, making the universe transparent and visible. This transition is marked by the emission of the cosmic microwave background radiation, which we can still detect today as the afterglow of the Big Bang.
Complete Question:
According to the Big Bang theory, after the "bang," the universe remained dark until about _____ later, when neutral atoms began to form.
If an engine operates on an input temperature of 800k and an exhaust temperature of 600k, calculate the efficiency of the engine.
Answer:
25.0 %
Explanation:
What is the difference between accurate data and reproducible data?
Answer:
Accuracy is ‘the state of being correct’ and on the other hand precision is ‘the state of being exact.
Explanation:
Accuracy shows the nearness of the measurement with the actual measurement while precision shows the nearness of an individual measurement with other measurements.
Accuracy focuses on the errors caused by the problem in the instrument. while precision is concerned with errors, which occurs periodically with no recognizable pattern.
If the measurement is precise but inaccurate, the result will not be the expected one. And if the result is accurate but imprecise, then there are huge variations in the measurements. And finally, if the actual measurement is neither accurate nor precise, then the result would not have correctness and exactness at the same time.
Water turning into steam represents what kind of change
The acceleration due to the earth's gravity, in si units, is 9.8 m/s2. in the absence of air friction, a ball is dropped from rest. its speed on striking the ground is exactly 60 m/s. for what time interval was the ball falling?
You may have noticed that when water boils you can see the bubbles that rise to the surface of the water.. what is inside these bubbles?
The bubbles that form and rise when water boils contain primarily water vapor. When the temperature reaches 100°C, the vapor pressure inside the bubbles equalizes with the atmospheric pressure, causing them to rise. This process is what we observe as boiling.
When water boils, you can see bubbles that rise to the surface. These bubbles contain water vapor. At lower temperatures, like 20°C, the bubbles start with some dissolved air and water vapor. As the temperature rises to boiling point (100°C), the amount of water vapor inside the bubbles increases because the vapor pressure reaches 1.00 atm, equalizing with atmospheric pressure. This causes the bubbles to grow and rise to the surface, where they burst, releasing water vapor into the air.
Glass is a _____ conductor of heat.
If there's nothing faster than light, how did the dark get there first
A 70 kg box is slid along the floor by a 400 N force. The coefficient of friction between the box and the floor is 0.50 when the box is sliding. Find the acceleration of the box
The acceleration of the box of mass 70 Kg sliding along the floor and havin 0.5 coefficient of friction is 0.81 m/s².
We'll begin by calculating the frictional force opposing the motion. This can be obtained as follow:Mass (m) = 70 Kg
Coefficient of friction (µ) = 0.5
Acceleration due to gravity (g) = 9.8 m/s²
Normal reaction (N) = mg = 70 × 9.8 = 686 N
Frictional force (F) =?F = µN
F = 0.5 × 686
F = 343 NThus the frictional force is 343 N.
Next, we shall determine the net force acting on the box. This can be obtained as follow:Force applied (F) = 400 N
Frictional force (Fբ) = 343 N
Net force (Fₙ) =?Fₙ = F – Fբ
Fₙ = 400 – 343
Fₙ = 57 NThus, the net force acting on the box is 57 N
Finally, we shall determine the acceleration of the box. This can be obtained as follow:Mass (m) = 70 Kg
Net force (Fₙ) = 57 N
Acceleration (a) =?Fₙ = ma
57 = 70 × a
Divide both side by 70
a = 57 / 70
a = 0.81 m/s²Therefore, the acceleration of the box is 0.81 m/s².
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What energy is calculated from an object's mass height and the acceleration due to gravity?
Jack tries to place magnets on the door of his refrigerator. He observes that the magnets don’t stick. He guesses that the door of the refrigerator is made of a nonmagnetic substance. What stage of scientific investigation does his guess represent?
ask questions
construct a hypothesis
explain the results
make observations
Answer:the one above
Explanation:
the one above
The bearing of a ship from a lighthouse was found to be n14 degrees14°e. after the ship sailed 7.27.2 miles dueâ south, the new bearing was n31 degrees31°e. find the distance between the ship and the lighthouse at each location.
To solve this problem, let us first assign some reference points. Let us say that initial position of the ship is called point A while the final position is called point B. While the position of the light house is called point L. Together they form a triangle.
The angles are:
angle LAB = 14°
angle ABL = (180 – 31)° = 149°
The lighthouse is at L.
The ship sails 7.2 miles to B.
We see that angle angle ALB = 180 – angle LAB – angle ABL
Therefore
angle ALB = 180 – 14 – 149 = 17°
Now in the triangle ABL, we use the Law of Sines:
AL / sin 149 = 7.2 / sin 17
AL = 12.68 miles
BL / sin 14 = 7.2 / sin 17
The question requires using bearings and trigonometry to calculate distances between a ship and a lighthouse at two points in time. We form two right-angled triangles with common sides, representing the initial distance, and apply trigonometric functions to solve the distances.
The question involves finding the distance between a ship and a lighthouse at two different locations using bearings. Initially, the bearing of the ship from the lighthouse is N14°E. After the ship travels 7.2 miles due south, the bearing from the lighthouse becomes N31°E. To solve this, you can create two right-angled triangles sharing a common side (the initial distance from the lighthouse) - the first triangle for the initial position and the second for the position after the ship's southward journey. You can then use trigonometry to solve for the distances.
To find the initial distance, consider the bearing N14°E as the angle from due north. This implies the ship is east of the lighthouse. Apply the cosine of 14° to calculate the adjacent side, which represents the initial distance from the lighthouse to the ship. Similarly, for the new bearing of N31°E, after sailing due south, the ship will be further east. Use the cosine of 31° for calculating the new distance to the lighthouse. These calculations will require the use of a calculator.
Using the new position distance and the southward travel of 7.2 miles, it is also possible to calculate the initial distance to the lighthouse before the ship moved southwards. Add the distances traveled eastward from the two positions of the ship to find this initial distance.
Compared with a force, a torque involves
According to statistics, currently there are approximately __________ drug users living in the United States.
A. 22 million
B. 15 million
C. 10 million
D. 5 million
A. 22 Million...........................................................
What causes a regular reflection?
A. Light waves strike a rough, uneven surface at a 45 degree angle and are reflected back at a 90 degree angle.
B. Parallel light waves strike a smooth, polished surface and reflect back in the same direction.
C. Parallel light waves strike a rough, uneven surface and reflect in different directions.
D. Light waves strike a smooth, polished surface at a 90 degree angle and are reflected back at a 45 degree angle.
Answer:
Option B. Parallel light waves strike a smooth, polished surface and reflect back in the same direction.
Explanation:
Thinking process:
Light possess a dual nature. It has got wave properties as well as particle (electron-like) properties. This means that light travels in pockets or quanta.
When lights hits a smooth shiny surface, it is immediately reflected back. This can be expressed by the wave equation:
[tex]sin i = sin r[/tex]
Where i is the incident ray - the ray that hits the surface
an r is the reflected ray - the ray that leaves the surface.
If the surface is polished and even, it means that the angle of incident is equal to the angle of reflection.
Hence option B is correct.
How long (in ns) does it take light to travel 1.30 m in vacuum?
A plane can fly 600 miles in the same time as it takes a car to go 120 miles. if the car travels 120 mph slower than the plane, find the speed of the plane.
an input force of 20 newtons is applied to a lever at a distance of 2 meters from the fulcrum and object 0.5 M away from the fulcrum and on the other side is lifted by the 20-N force what is the output force?
A railroad freight car with a mass of 29,000 kg is moving at 2.2 m/s when it runs into another car with a mass of 30,000 kg the second car is at rest the cars locked together what is the final velocity
Answer:
1.1 m/s for apex 4.1.6.
Explanation:
i clicked that option and it was right
How much heat transfer occurs from a system, if its internal energy decreased by 150 j while it was doing 30.0 j of work?
Hence the heat transfer that occurs from a system will be -120 J.
What is heat transfer?Heat transfer refers to the movement of heat. The flow of heat across a system's boundary is due to a temperature differential between the system and its surroundings.
The given data in the problem is;
ΔU is the internal energy -150 J
W is the work fon = - 30 J
Q is the heat transfer that occurs from a system
The internal energy of the system is found as;
[tex]\rm \triangle U = Q + W \\\\-150 =Q-30 \\\\ Q=-120 \ J[/tex]
The heat transfer that occurs from a system will be -120 J.
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About one-third of the toxic metal, mercury (hg), is released into the air from natural sources, such as rocks, soil, volcanoes, and the ocean. the remaining two-thirds comes from ____.
a. human activities
b. waste from livestock
c. airplane exhaust
d. automobile exhaust
e. mercury-rich plants
About one-third of the toxic metal, mercury (Hg), is released into the air from natural sources, such as rocks, soil, volcanoes, and the ocean. the remaining two-thirds comes from human activities.
What is mercury?Mercury is the 80th element in periodic table. It is a heavy metal but exists as liquid in room temperature. Mercury is a transition metal having wide applications in various industries.
Mercury is toxic in nature and reported to be dangerous to human health, even causes death by concentric exposure. Global mercury contamination is a result of human activities including mining and the burning of fossil fuels.
Mercury that is released into the air eventually sinks into the ground or is washed into the water. Once deposited, specific microbes can transform it into methylmercury, a very poisonous form that accumulates in fish, shellfish, and animals that consume fish.
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The distance between twin satellites that were originally 150 meters apart are now 300 meters apart. Which best describes the gravitational force between the twin satellites? A) it increased by 1/2 B) it decreased by 1/4 C) it increased by a factor of 2 D) it decreased by a factor of 4
Answer : (B) it decreased by 1/4
Explanation :
It is given that :
The distance between twin satellites that were originally 150 meters apart are now 300 meters apart.
When the satellites are 150 m apart then the gravitational force is :
[tex]F=G\dfrac{m_1m_2}{(150\ m) ^2}[/tex]..........(1)
Similarly, when the satellites are 300 m apart then the gravitational force is :
[tex]F'=G\dfrac{m_1m_2}{(300\ m) ^2}[/tex]...........(2)
From eq (1) and (2)
[tex]\dfrac{F_c}{F_c'}=4[/tex]
[tex]F_c'=\dfrac{F_c}{4}[/tex]
So, the gravitational force between the twin satellites is decreased by 1/4.
Hence, the correct option is (b).
Answer:
B: it decreased by 1/4
Explanation:
Provides some background for this problem. a ball is thrown vertically upward, which is the positive direction. a little later it returns to its point of release. the ball is in the air for a total time of 7.70 s. what is its initial velocity? neglect air resistance.
A ball is thrown from ground level so as to just clear wall 4m height at distance 4m from wall and falls 14 m from wall . Velocity of ball ?
As a solid element melts, the atoms become __________ and they have __________ attraction for one another. more separated, more more separated, less closer together, more closer together, less larger, greater
You place a book on top of a spring and push down, compressing the spring by 10 cm. When you let go of the book, it is pushed up by the spring. Which statement describes what happens to the energy of the spring-book-system?
Answer: The gravitational potential energy of the system increases.
Explanation:
If you are riding in a vehicle equipped with a lap belt and also a separate shoulder belt, you are
Riding in a vehicle with a lap belt and a separate shoulder belt provides significant protection in car accidents. The lap belt secures the lower body while the shoulder belt secures the upper body.
Explanation:If you are riding in a vehicle equipped with a lap belt and also a separate shoulder belt, you are using one of the most effective safety measures for passenger vehicles. These belts, when used together, greatly reduce the chance of serious injury or death in a car accident. The lap belt secures your lower body, preventing you from sliding forward or sideways, while the shoulder belt protects your upper body, preventing you from being ejected from the vehicle or hitting the interior elements during a collision.
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What is the value of work done on an object when a 10-newton force moves it 30 meters and the angle between the force and the displacement is 25°?
A 900-N lawn roller is to be pulled over a 5-cm (high) curb. Radius of roller is 25 cm. What minimum pulling force is needed if angle made by handle is (a) 0 deg (b) 30 degrees?
Final answer:
When the handle angle is 0 degrees, no minimum pulling force is needed. When the handle angle is 30 degrees, the minimum pulling force needed is 36,000 N.
Explanation:
To calculate the minimum pulling force needed to pull a 900-N lawn roller over a 5-cm curb, we can use trigonometry and the concept of work. The work done to lift the roller over the curb is equal to the force applied multiplied by the distance moved in the direction of the force. Since the force is perpendicular to the direction of motion when the handle angle is 0 degrees, no work is done.
Therefore, no minimum pulling force is needed. When the handle angle is 30 degrees, the work done is equal to the force applied multiplied by the vertical distance lifted. Using trigonometry, the vertical distance lifted is given by 5 cm multiplied by the sine of 30 degrees, which is 2.5 cm (or 0.025 m). Therefore, the minimum pulling force needed is the work done divided by the distance moved, which is 900 N divided by 0.025 m, equal to 36,000 N.
What substance is reduced in a lead storage battery?
In lead acid battery, chemical reactions are induced to do work on charge and produce a voltage difference between the two output terminals.
In a lead storage battery, the negative terminal is composed of lead electrode (Pb2+) while in the positive terminal it is composed of lead dioxide electrode (PbO2).
The chemical half reactions in each electrode are:
Negative Terminal: Pb2+ + SO4(2-) ---> PbSO4 + 2e
Lead electrode is oxidized to supply electrons.
Positive Terminal: PbO2 + H2SO4 + e ---> PbSO4
Lead dioxide electrode is reduced by the addition of electrons.
Answer: Lead dioxide is reduced.
The number of significant figures in the measurement 0.000 305 kg is
six.
two.
seven.
three.
We have that from the Question"The number of significant figures in the measurement 0.000 305 kg is " it can be said that The number of significant figures in the measurement 0.000 305 kg is
3Option DFrom the Question we are told
The number of significant figures in the measurement 0.000 305 kg is
six. two. seven. three.Generally the rule of significant number state that
Leading zeros are NOT significant.Therefore
We cont all none zero number
We have
X=3
Therefore
The number of significant figures in the measurement 0.000 305 kg is
3Option DFor more information on this visit
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