Final answer:
Dark matter is an unseen substance that makes up about 90% of the universe's mass, detectable through its gravitational effects on visible matter. It exists in a halo around galaxies and is essential for understanding the universe's composition and expansion fate.
Explanation:
The unseen matter that may constitute as much as 90% of the universe is known as dark matter. This dark matter is not directly observable because it does not emit or reflect any electromagnetic radiation. However, its existence is inferred from gravitational effects on visible matter, radiation, and the large-scale structure of the universe.
For example, galaxies contain far more mass than can be accounted for by the visible objects we can observe, and this extra mass is attributed to dark matter. The rapid rotation of stars on the outskirts of galaxies is one such gravitational effect indicating the presence of dark matter in a halo around the galaxies.
Discovering the true nature of dark matter is crucial as it may provide insights into particle physics and cosmology. There are theories that dark matter could be composed of neutrinos with a small mass or entirely new types of particles that have never been detected.
The understanding and evidence of dark matter continue to evolve, highlighting its importance in the universe's critical density and its possible role in the ultimate fate of the cosmic expansion.
Carbon burns in the presence of oxygen to give carbon dioxide. Which chemical equation describes this reaction?
Answer with Explanation:
The Statement of Chemical Reaction is:
Carbon burns in the presence of oxygen to give carbon dioxide.
Writing it in terms of Chemical Reaction
[tex]C (\text{Carbon}) +O_{2}(\text{Two Atoms of Oxygen})=CO_{2}[/tex]
That is Carbon when combines with two molecules of Oxygen gives Carbon Dioxide.
A car left point a at 7:30 am and arrived at point b, 162 miles away at 10:30 am. what was its average speed in miles per hour? 53 54 55 56 skip
Answer: 54 miles per hour
Explanation:
Given: Distance = 162 miles
As the car left point a at 7:30 am and arrived at point b.
Time taken to travel from point a to b = 3 hours
Therefore, the average speed =[tex]\frac{\text{total distance}}{\text{total time}}[/tex]
[tex]=\frac{162}{3}=54\text{ miles per hour}[/tex]
Hence, the average speed = 54 miles per hour
The average speed of the car, which travelled 162 miles over a period of 3 hours, is calculated as total distance divided by total time -- in this case, 54 miles per hour.
Explanation:To calculate the average speed of the car, we divide the total distance travelled by the total time taken. In this case, the car travelled 162 miles between 7:30 am and 10:30 am, which is a period of 3 hours. Therefore, we calculate the average speed as follows: 162 miles / 3 hours = 54 miles per hour. So, the car's average speed over the whole journey from point A to point B was 54 miles per hour. In the context of this problem, 'average speed' is a measure of the total distance covered in a given time period, regardless of changes in speed or direction over the course of the journey.
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Why does helium have more spectral lines than hydrogen?
This is because Helium has two valence electrons compared to Hydrogen which has only one. Helium has more energy levels for an electron to jump thus more spectral lines to occur. The spectral lines relating to each change of energy level would be more grouped together and hence the greater chance of them falling in the visible range.
Helium has more spectral lines than hydrogen due to the differences in their atomic structure and electron configurations, leading to a higher number of possible transitions and spectral lines.
Helium has more spectral lines than hydrogen because of the differences in the atomic structure of the two elements. While both elements exhibit similar spectral series, helium has two series of lines for every one series observed in hydrogen. This is due to the presence of two electrons in helium compared to one in hydrogen, resulting in more possible transitions and spectral lines.
How much time does it take for the bill to fall beyond her grasp? the length of a bill is 16 cm?
The greatest ocean depths on the earth are found in the marianas trench near the philippines, where the depth of the bottom of the trench is about 11.0 km. calculate the pressure due to the ocean at a depth of 9.1 km, assuming seawater density is constant all the way down. (the validity of the assumption of constant density is examined in one of the integrated concept problems.)
What level of intensity is bicycling 5-9 mph on level terrain?
Which physical layer of earth is broken into tectonic plates?
The lithosphere, encompassing Earth's crust and the uppermost rigid portion of the mantle, is the layer divided into tectonic plates. These plates move due to the convection of the mantle and are responsible for many geological processes.
Explanation:The physical layer of Earth that is broken into tectonic plates is known as the lithosphere, which includes the crust and the uppermost, rigid portion of the mantle. The lithosphere is about 100 kilometers thick and is broken into several tectonic plates that cover Earth's surface, including both continental and oceanic crust.
These tectonic plates fit together like a jigsaw puzzle and move due to the process of mantle convection, where heat from Earth's interior causes the upward flow of warmer mantle material and the downward sinking of cooler material. This movement can cause the plates to drift apart, collide, or grind past each other, leading to various geological phenomena such as earthquakes, volcanic activity, and the formation of mountain ranges.
The asthenosphere beneath the lithosphere is involved in the movement of these plates as well; it acts as a soft, ductile layer allowing the rigid plates of the lithosphere to move over it. The slow but steady motion of tectonic plates is driven by numerous forces, including the heat transfer from Earth's interior which is an essential aspect of planet's cooling system.
According to the big bang theory, after the "bang," the universe remained dark until
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.
What forms when an artesian well begins to push out enough water that gravity causes it to flow to a lower region?
An artesian well is a well drilled into an artesian aquifer. An artesian aquifer is a small aquifer which contains groundwater under positive pressure. Since the water is under positive pressure, this forces the water level in the well to rise above the water surface up to a point where hydrostatic equilibrium is reached. This results in the formations of “Springs”.
Answer: Spring
Final answer:
An artesian well can create a spring when the pressure is sufficient to allow water to flow to the surface. This event has the potential to affect the local water table and contribute to larger water management challenges such as saltwater intrusion and subsidence.
Explanation:
When an artesian well begins to push out enough water that gravity causes it to flow to a lower region, a spring is formed. This occurs when the pressure within the confined aquifer becomes greater than the pressure exerted by the atmosphere above it, allowing the groundwater to flow out without the need for pumping. If the water finds its way to the surface, it can emerge as a spring and potentially form a stream, depending on the topography and geology of the area.
The creation of a spring due to the development of an artesian well may alter the local water table and potentially reduce the volume of water in other nearby wells or surface water bodies. Associated issues such as groundwater mining, saltwater intrusion, and damage through subsidence and sinkholes can arise if the water extraction is not managed sustainably, contributing to the broader context of a water supply crisis.
Electromagnetic waves are ________ waves.
a. longitudinal
b. surface
c. primary
d. transverse
A person is riding an elevator downward at a constant speed. compare using full sentences the amount of force acting upward on the person to the amount of force acting downward on the person
you want to get more physically fit but often make excuses for why you don't have time to be active what strategy can help with this problem
Answer:
Find an activity you enjoy and make it a priority in your schedule
Explanation:
In order to catch a fast-moving softball with your bare hand, you extend your hand forward just before the catch and then let the ball ride backward with your hand. doing this reduces the catching force because the
Final answer:
Catching a fast-moving softball with an extended hand moving backward reduces the catching force because this technique increases the time over which the collision occurs, thus lowering the force applied to the hand according to the impulse-momentum theorem.
Explanation:
The student's question pertains to the physics concept of impulse and how it applies to catching a fast-moving softball with one's bare hands. When you move your hand backward upon catching the ball, you are increasing the time over which the collision between your hand and the ball occurs. According to the impulse-momentum theorem, the impulse on an object is equal to the change in momentum of the object, which is the product of the mass and change in velocity (force applied over a period of time). By increasing the time, the force exerted on your hand by the ball decreases, making it less painful and reducing the likelihood of injury.
Using the formula impulse = force × time, by increasing the time during which the force is applied (the time during which your hand moves backward), you are effectively spreading out the force over a longer period, and thus, the peak force felt by your hand is lower. This is similar to the concept of crumple zones in cars which extend the time of impact and reduce the force felt by the occupants.
Therefore, when catching a fast-moving softball with your hand, extending your hand forward and allowing the ball to ride backward with your hand reduces the catching force due to the longer duration over which the force is applied, resulting in a smaller impulse felt by your hand. This is why this technique is often used by players to catch high-speed balls safely.
The rate constant of a first-order process that has a half-life of 3.50 min is __________ s-1.
The rate constant of the first-order process that has a half-life of 3.50 min is approximately 0.00330 [tex]s^{-1}[/tex].
The rate constant of a first-order process is related to its half-life through the equation:
k = 0.693 / [tex]t^{\frac{1}{2}[/tex]Given that the half-life ([tex]t{\frac{1}{2}[/tex]) of the process is 3.50 minutes, we need to convert this time into seconds:
3.50 min x 60 s/min = 210 sNow, substituting the half-life into the equation for the rate constant:
k = 0.693 / 210 sCalculating the rate constant:
k ≈ 0.00330 [tex]s^{-1}[/tex]Therefore, the rate constant of the first-order process is approximately 0.00330 [tex]s^{-1}[/tex].
Heat from the sun causes ________________ of water from the ocean and land surfaces
To what temperature would you have to heat a brass rod for it to be 1.8 % longer than it is at 30 ∘c?
We have to heat a brass rod at 982.4[tex]\rm ^\circ C[/tex] for it to be 1.8 % longer than it is at 30.
Given :
Brass rod is 1.8 % longer than it is at 30[tex]\rm ^\circ C[/tex].
Solution :
We know that,
[tex]\rm \dfrac{\Delta L}{L_0}=\alpha \Delta T[/tex]
[tex]\rm \dfrac{\Delta L}{L_0}=\alpha ( T_2-T_1)[/tex] ---- (1)
Where, [tex]\rm \Delta L[/tex] is the elongation,
[tex]L_0[/tex] is the original length,
[tex]\alpha[/tex] is the coefficient of linear expansion. For brass,
[tex]\rm \alpha = 18.9\times 10^-^6/^\circ C[/tex],
[tex]\rm \Delta T[/tex] is the change in temperature.
1.8 % length expansion means:
[tex]\rm \dfrac{\Delta L}{L_0} = 0.018[/tex]
Now put the values of
[tex]\rm \alpha ,\;\dfrac{\Delta L}{L_0},\;and\;T_1[/tex] in equation (1) we get:
[tex]\rm 0.018 = 18.9\times 10^-^6 \times(T_2 - 30)[/tex]
[tex]\rm T_2 = 982.4\; ^\circ C[/tex]
We have to heat a brass rod at 982.4[tex]\rm ^\circ C[/tex] for it to be 1.8 % longer than it is at 30.
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investigate the relationship between volume and pressure of a gas at a constant temperature.
Hurricane sandy produced some of the greatest destruction along the new jersey coast in communities situated along narrow strips of land between the beach and a coastal lagoon to the west. these communities were vulnerable because they were built on low-lying terrane of ________.
The correct answer to fill in the blank would be:
“a barrier island”
Barrier islands are coastal landforms and a category of dune system that are remarkably even or lumpy areas of sand that was formed by wave and tidal actions that are parallel to the mainland coast. Due to this feature, there are no enough sand blockades to minimize the destruction by Hurricane Sandy.
An engineer weighs a sample of mercury (ρ = 13.6 × 103 kg/m3 ) and finds that the weight of the sample is 6.0 n. what is the sample’s volume? the acceleration of gravity is 9.81 m/s 2 . answer in units of m3 .
The volume of the mercury sample is approximately 4.28 × 10⁻⁶ m³.
Explanation:To find the volume of the mercury sample, we can use the formula: density = mass/volume. Rearranging the formula, we have volume = mass/density. The weight of the sample is 6.0 N, and with the acceleration due to gravity being 9.81 m/s², we can calculate the mass of the sample using the formula weight = mass × acceleration due to gravity. Therefore, mass = weight/acceleration due to gravity. Plugging in the values, we get mass = 6.0 N/(9.81 m/s²).
Next, we substitute the calculated mass and the given density into the formula to find the volume: volume = mass/density. With the calculated mass and the given density of 13.6 × 10³ kg/m³, we get volume = mass/density = (6.0 N/(9.81 m/s²))/(13.6 × 10³ kg/m³).
Simplifying the expression, the volume of the sample is approximately 4.28 × 10⁻⁶ m³.
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A boy kicks a football with an initial velocity of 28.0 m/s at an angle of 30.0o above the horizontal. what is the highest elevation reached by the football in its trajectory?
The highest elevation reached by the football in its trajectory is approximately 20.7 meters.
Explanation:To determine the highest elevation reached by the football, we can use the kinematic equations for projectile motion. The initial velocity of the ball can be broken down into its horizontal and vertical components using trigonometry.
The horizontal component of the initial velocity is 28.0 m/s * cos(30.0°) and the vertical component is 28.0 m/s * sin(30.0°). Since there is no vertical acceleration at the highest point of the trajectory, the vertical component of the velocity is zero. We can use this information to find the time it takes for the ball to reach its highest elevation.
Using the equation vf = vi + at, where vf is the final velocity (zero), vi is the initial velocity (vertical component), a is the acceleration (acceleration due to gravity: -9.8 m/s^2), and t is the time, we can solve for t. Plugging in the values, we get:
0 = 28.0 m/s * sin(30.0°) - 9.8 m/s^2 * t
Simplifying and solving for t, we find that t = 2.86 seconds.
Now, we can use the equation hf = hi + vit + (1/2)at^2, where hf is the final height (highest elevation), hi is the initial height (0 m since the ball starts on the ground), vi is the initial velocity (vertical component), a is the acceleration (acceleration due to gravity), and t is the time. Plugging in the values, we get:
hf = 0 + 28.0 m/s * sin(30.0°) * 2.86 seconds + (1/2)(-9.8 m/s^2)(2.86 seconds)^2
Simplifying, we find that the highest elevation reached by the football is approximately 20.7 meters.
An iron block of mass 45.87 kg is heated from 7 c to 218
c. if the specific heat of iron is 450 j-1 kg k-1 then how much energy is required
The amount of energy required to heat a 45.87 kg iron block from 7°C to 218°C, given a specific heat capacity of 450 J kg-1 K-1 , is 4364065.5 Joules.
Explanation:The amount of heat energy required to change the temperature of a substance can be calculated using the formula Q = mcΔT, where:
Q is the heat energym is the mass of the substancec is the specific heat capacityΔT is the change in temperatureGiven that the mass of the iron block (m) is 45.87 kg, the specific heat of iron (c) is 450 J kg-1 K-1, and the change in temperature (ΔT = T2 - T1) is (218 - 7) or 211°C, which is equivalent to 211 K in terms of heat calculations. Substituting these values into the formula, we get:
Q = 45.87 kg * 450 J kg-1 K-1 * 211 K = 4364065.5 Joules
So, it would require 4364065.5 Joules of energy to heat the iron block from 7°C to 218°C.
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From the top of the engineering building, you throw a ball vertically upward. the ball strikes the ground 4.00 s later. the engineering building is 35.0 m tall. what is the initial velocity of the ball?
Images to promote fitness often lead readers to a certain conclusion about appearance. Which of the following is a practice teens most frequently experience?
A focus on feeling good about their looks A focus on their appearance A focus on feeling great inside A focus on their health and fitnessA tipping point in the disappearance of tropical rainforests would be
When atoms lose more than one electron, the ionization energy to remove the second electron is always more than the ionization energy to remove the first. similarly, the ionization energy to remove the third electron is more than the second and so on. however, the increases in ionization energy upon the removal of subsequent electrons is not necessarily uniform?
How should the flight controls be held while taxiing a tricycle-gear equipped airplane with a left quartering tailwind?
To taxi a tricycle-gear equipped airplane with a left quartering tailwind, hold the elevator control fully forward and the aileron control to the left - to prevent the wind from lifting the tail or wing.
Explanation:When taxiing a tricycle-gear equipped airplane with a left quartering tailwind, the flight controls should be held in a specific manner to maintain control of the aircraft. The elevator control should be fully forward and the aileron control turned to the left. This means the yoke or stick should be pushed forward and turned to the left.
Why so? This configuration of controls help prevent the wind from getting under the tail or wing and causing a loss of control. The left aileron up bubble helps prevent the left wing from being lifted by the wind. The elevator down bubble will prevent the wind from getting beneath the tail and lifting the nose.
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A 1500-W heater is connected to a 120-V line for 2.0 hours. How much heat energy is produced?
How does the magnetic force on a stationary charged particle compare to the magnetic force on a moving charged particle? A. There is no magnetic force on a moving charged particle. B. There is no magnetic force on a stationary charged particle. C. The force on a moving particle is multiplied by the magnitude of the velocity. D. The force on a moving particle is twice the force on an identical stationary particle.
Final answer:
The magnetic force on a stationary charged particle is zero, while the magnetic force on a moving charged particle is non-zero. When charges are stationary, their electric fields do not affect magnets. However, when charges move, they produce magnetic fields that exert forces on other magnets.
Explanation:
The magnetic force on a stationary charged particle is zero, while the magnetic force on a moving charged particle is non-zero. When charges are stationary, their electric fields do not affect magnets. However, when charges move, they produce magnetic fields that exert forces on other magnets. The magnitude of the magnetic force on a charge q moving at a speed v in a magnetic field of strength B is given by F = quB sin θ.
Potassium hydroxide (KOH) and hydrochloric acid (HCl) react in a beaker. They form potassium chloride (KCl) and water (H2O). What type of reaction is this? synthesis reaction
double replacement reaction
single replacement reaction
decomposition reaction
Answer: double replacement reaction
Explanation:
1. Synthesis reaction is a chemical reaction in which two reactants are combining to form one product.
Example: [tex]Li_2O+CO_2\rightarrow Li_2CO_3[/tex]
2. Double displacement reaction is one in which exchange of ions take place. Neutralization is a special type of double displacement where acid reacts with base to form salt and water.
Example: [tex]KOH(aq)+HCl(aq)\rightarrow KCl(aq)+H_2O(l)[/tex]
3. Single replacement reaction is a chemical reaction in which more reactive element displaces the less reactive element from its salt solution.
Example: [tex]Zn+2HCl\rightarrow ZnCl_2+H_2[/tex]
4. Decomposition is a type of chemical reaction in which one reactant gives two or more than two products.
Example: [tex]Li_2CO_3\rightarrow Li_2O+CO_2[/tex]
When condensation rates decrease, causing fewer clouds to form, how might humans change their behavior?
Explanation:
Humans might hold picnic outside in the bright sunny daylight and enjoy their day with family and friends. People will relax and will spend time with their near and dear ones. Less condensation means no rainfall, so people will also do few works that they have been willing to do but could not do due to rainfall. Thus people will be in a happy mood doing their work and spending their time with close ones. A sense of positiveness and happiness will surround the atmosphere.