an ideal spring is used to fire a 15.0 g pellet horizontally. the spring has a spring constant of 20 n/m and is initially compressed by 7.0 cm. the kinetic energy of the pellet as it leaves the spring is:
The pellet has a kinetic energy of 4.9 10-2 J as it exits the spring.
The kinetic energy is absent.Kinetic energy is the term for the energy present in an object in motion. Examples of kinetic energy include you walking down the street, the globe rotating around the sun, and motion in space. The relationship between kinetic energy and an object's mass and square of its velocity is direct: K.E. = 1/2 m v2.
Calculation:To calculate the kinetic energy of the pellet, solve the energy conservation equation using the necessary variables as substitutes.
KE = EPE
KE = 1/2 kx²
KE = 1/2(20N/m) (7cm ×1/100cm)²
KE = 4.9 × 10⁻²J.
To know more about kinetic energy visit:-
https://brainly.com/question/26472013
#SPJ4
in the double-slit experiment with electrons, suppose that the observer uses a detector to determine through which slit the electron actually passes. does this affect the outcome of the experiment, and why or why not?
No matter the detector, the pattern on the screen is still non-interference.
In the double-slit experiment, how does the detector operate?In the double-double slit experiment, photons are momentum entangled and can share information about each other's which-slit paths if one of them is found near any double slit. If a single slit of a double-slit is blocked, it is possible to determine the which-slit path from the simultaneous photon detection.
What impact does observation have on the double-slit test?In quantum physics, the double-slit experiment serves as a prominent illustration of the observer effect. The measured outcomes of this experiment can alter if quantum phenomena are observed, according to physicists.
To know more about double-slit experiment visit:-
https://brainly.com/question/28108126
#SPJ4
1. How did the rock of the Great Plains and Rocky Mountains form?Choose the claim you can eliminate. ResponsesThey formed as one rock formation, and then something separated them.They formed as one rock formation, and then something separated them.One rock formation formed before the other. Then, the minerals from the older rock became part of the younger rock.One rock formation formed before the other. Then, the minerals from the older rock became part of the younger rock.3What do we still need to know in order to determine why the two rock formations have such similar minerals?Evidence Card E: Rocky Mountains. Photo of the Rocky Mountains. Observations: The large mountains have jagged tops. The chunks of rock vary in size. The rock appears to be light and dark gray. There is a forest at base of the mountains.Evidence Card C: Rock from the Rocky Mountains. Photo of a rose-colored rock with dark veins. Observations: The rock contains visible pink, dark gray, and light brown grains. The grains fit together. The grains have sharp edges. There are no bubbles or fossils in this sample.2Why can we eliminate the claim you selected?
Rocky Mountains and Great Plains rock came together to form one rock formation, but then something tore it apart. The first claim is true while the second claim needs to be eliminated
What are rocky mountains?It should be remembered that the Rocky Mountains and the Great Plains are two separate rock formations that did not form simultaneously. The older rock's minerals were not incorporated into the younger rock as a result.
After combining the rock from the Rocky Mountains and the Great Plains to form one formation, something tore it apart. As a result, the second claim must be rejected because it is false.
For more information on rocky mountains kindly visit to
https://brainly.com/question/13438263
#SPJ1
which of the following most directly shows how affects physics
Air bags protect people during car crashes is an example that shows how physics affects society. The correct option to this question is D.
How physics is involved in air bags helpful?Your vehicle and everything inside of it are moving in one direction; therefore, for it to stop, force must be applied gradually in the other direction over time. This happens very quickly in an accident, and because the opposing force only has a little period of time to operate on the vehicle, the force is stronger. The airbag system is made to protect you from the damaging pressures that an accident can exert on you.Your airbag system is made up of three primary parts: the bag, the inflator, and the sensor. Before the airbag inflates, the sensor must detect a collision force roughly equivalent to running into a brick wall at a speed of 10 to 15 miles per hour.For more information on physics kindly visit to
https://brainly.com/question/28600368
#SPJ1
Complete question: Which of the following most directly shows how physics affects society
A.a perfume company designs a new fragrance
B.a patient is treated by acupuncture for an illness
C.gardeners uses fertilizers to help plants grow
D.air bags protect people during car crashes
Identify each attribute as belonging to either a primary or secondary group, keeping in mind Charles Horton Cooley's theory of groups. Primary Group(s) Drag appropriate answer(s) here high level of intimacy role play by members impersonal relationships instrumental in purpose + strong sense of unity and commitment Drag appropriate answer(s) here Secondary Group(s)
Primary groups: high degrees of dedication, togetherness, and intimacy. Typically huge, impersonal, and frequently including secondary groups
A secondary group is one based on shared goals or interests in which the members are infrequently, if ever, in face-to-face contact with each other, such as a club. A primary group is a small group based primarily on long-term face-to-face interaction and typically based on affiliation, such as a family or a friendship group. Primary groups, in Cooley's opinion, are the most important in our life. The main group is typically quite small and consists of people who interact face-to-face in emotional ways over an extended period of time. This group fulfils expressive rather than pragmatic requirements—emotional demands. A main group consists
To learn more about secondary please click on below link
https://brainly.com/question/336747
#SPJ4
What does solar and wind have in common?
In the field of renewable energy, wind and solar energy are major actors. They are free energy sources, limitless, and most of all, they reduce carbon emissions from fossil fuels.
How are wind and sun energy related?Wind energy is part of solar energy. The earth's atmosphere is heated by the sun, and wind is produced as a result of the earth's rotation around the sun. During the day, the air above the land warms up more quickly than the air above the sea.
Are solar and wind energy equivalent?Technically, wind energy is a type of solar energy. Hot air rises when the uneven surface of the Earth is heated by the sun's radiation, while cold air settles. The result of this difference in air pressure is wind, which is a kinetic (based on motion) source of energy. A windmill take hold of that kinetic energy.
To know more about source of energy visit:-
https://brainly.com/question/10483137
#SPJ4
A ship's propeller of diameter 3 m makes 10.6 revolutions in 30
s. What is the angular velocity of the propeller?
a 90.0 rad/s
b 31.8 rad/s
c 2.22 rad/s
d 66.7 rad/s
Answer:
Approximately [tex]2.22\; {\rm rad\cdot s^{-1}}[/tex].
Explanation:
Each revolution increases the angular displacement of the propeller by [tex]2\,\pi[/tex] radians. Therefore, after [tex]10.6[/tex] revolutions, the angular displacement of the propeller will be [tex](10.6)\, (2\, \pi) = 21.2\,\pi[/tex] radians.
Divide angular displacement by the duration to find the angular velocity of this propeller:
[tex]\begin{aligned}\frac{21.2\, \pi\; {\rm rad}}{30\; {\rm s}} \approx 2.22\; {\rm rad\cdot s^{-1}} \end{aligned}[/tex].
How did sonar change the world?
Sound Navigation and Ranging is referred to as SONAR. It is a method used to find things, navigate, or communicate below the surface of the water. It makes advantage of the Echo concept.
Why is sonar a valuable tool?
Sound waves are used by sonar to "see" in the water.
Sonar is mainly used by NOAA scientists to create nautical charts, find underwater navigational hazards, find and map things on the bottom like shipwrecks, and map the actual seafloor. Nearby objects that block the sound waves' passage cause them to reflect back off of them. The distance to the item is determined using the timing of the sound wave's transmission and reception, the speed of sound in water, the angle of the echo, and the change in frequency.
To know more about sonar, visit:
brainly.com/question/20510435
#SPJ4
Which of the following definitions best describes the concept of work?(a) the flow of energy from one object or substance to another due to a difference in temperature.(b) the flow of energy from one body to another through uniform molecular motion.(c) the force associated with molecular motion.(d) the random motion of molecules in a gas at low pressure.
The mass of the particles that a river can transport is proportional to the sixth power of the speed of the river. A certain river normally flows at a speed of 2 miles per hour. What must its speed be in order to transport particles that are 15 times as massive as usual? round your answer to the nearest hundredth.
Let m and s stand in for mass and speed, respectively. so that,
Its speed must therefore be around 6.58 miles per hour.
m = k
where k is the proportionality constant.
Speed equals 4 miles per hour for a specific river.
m = k
m = 1024k ............ 1
transporting particles with a mass 12 times greater than usual;
12m = k
m = ............. 2
Thus,
= 1024 k
= 12 x 1024
= 12288
12288
s = 6.5750
6.58 miles per hour is s.
Its speed must therefore be around 6.58 miles per hour.
To learn more about mass please click on below link
https://brainly.com/question/19694949
#SPJ4
10.A constant force is applied to a ball of mass m. The velocity of the ball changes from ν1 to ν2. The impulse received by the ball is
A. m(ν1 + ν2).
B. m(ν1 - ν2).
C. m(ν1^2 + ν2^2).
D. m(ν1^2 - ν2^2).
The velocity of the ball changes from ν₁ to ν₂ then the impulse received by the ball is m(ν₂ - ν₁).
What is impulse?Impulse received by the object can be described as the integral of a force over the time for which it acts. Impulse can be defined as also a vector quantity since the force is a vector parameter.
Impulse can be exerted on an object that produces an equivalent vector change in the linear momentum.
The S.I. unit of impulse can be denoted as N⋅s Newton second and the dimensionally unit of momentum is kg⋅m/s. A resultant force provides acceleration to the object and changes the velocity of an object for as long as it acts.
The change in the linear momentum of an object is equal to the impulse.
I = ΔP = m(ν₂ - ν₁).
Learn more about Impulse, here:
brainly.com/question/16980676
#SPJ1
if the fundamental frequency of a note is 200 hz, what is the frequency of the third harmonic?
The second harmonic f₂ is 400 Hz, the third harmonic f₃ is 600 Hz if the fundamental frequency is 200 Hz.
Only at precise vibrational frequencies, sometimes referred to as harmonic frequencies or simply harmonics, do these patterns emerge within the item or instrument. The ensuing disturbance of the medium at any frequency other than a harmonic frequency is erratic and non-repeating.
f₁ = 200hz
The lowest frequency of a periodic waveform is known as the fundamental frequency, also known as just the fundamental. The musical pitch of a note that is heard as the lowest partial existent in music is referred to as the fundamental. The fundamental frequency, or frequency of the difference between adjacent frequencies, in terms of a superposition of sinusoids is the lowest frequency sinusoidal in the total of harmonically linked frequencies. The fundamental, which denotes the lowest frequency counting from zero, is sometimes shortened as f₀. It is more typical to shorten it to f1, the first harmonic, in other instances. The zeroth harmonic in this situation would be 0 Hz.
Therefore, the second harmonic is f₂= 2f₁
f₂ = 2 *200hz = 400hz
f₃ = 3*200hz = 600hz
To know more about frequency
https://brainly.com/question/9253932
#SPJ4
under what conditions might a pilot expect the possibility of hydroplaning? a. when departing a grooved runway with less than a thousandth of an inch of water. b. when landing on a wet runway that is covered in rubber from previous landings. c. when the adiabatic lapse rate is high, and steam is rising from the landing surface.
When landing on a wet runway that is covered in rubber from previous landings.
What speed puts you in the greatest risk of hydroplaning?The majority of auto safety experts concur that hydroplaning would be most likely to happen at speeds greater than 35 mph.As soon when the first droplets land on your windshield, drastically reduce your speed.
Do heavier automobiles hydroplane more frequently?Vehicle weight: A vehicle has a greater tendency to hydroplane the lighter it is.Asphalt without grooves is more likely to hydroplane than concrete with ribs or grooves.
To know more about hydroplaning visit:
https://brainly.com/question/29157933
#SPJ4
What is needed in a market for a good to be considered elastic?
If the amount demand of a product changes more than proportionally as its price rises or falls, then it is said to be elastic.
How is a market made elastic?The more replacements there are for an item, more elastic the good is, according to definition of an elastic good, which is where change in price results in a large movement in demand. Price elasticity of demand is determined by dividing percentage change in quantity required by the percentage change in price.
Products like cars, appliances, and luxury items that are rarely purchased are examples of elastic commodities. In the event that the cost of these products is momentarily high, consumers may decide to put off buying.
To know more about elastic goods, refer
https://brainly.com/question/29549068
#SPJ4
What is the approximate wavelength range of thermal radiation Mcq?
Thermal radiation has a wavelength range of 7700A to 4106A.A emission if electromagnetic waves by all stuff with a temperature greater that absolute zero is known as thermal radiation.
What roughly is the heat radiation wavelength range?Thermal electromagnetic radiation is radiation with wavelengths between 0.1 and 100 m that is emitted by all matter that is not at absolute zero.All of the infrared and visible spectrums, as well as some ultraviolet (UV), are included (IR).
What is the heat source's radiative energy's approximate wavelength?Thermal radiation, or radiation heat transfer, is defined as radiation having wavelengths between 0.1 and 100 m.The entire visible, infrared, and some ultraviolet spectrums are all included in thermal radiation.
To know more about thermal radiation visit:
https://brainly.com/question/24200572
#SPJ4
How do you calculate frequency and rate?
Divide the number of times the event happens over the period of time to determine the frequency.
What is the rate of frequency?The frequency index is the number of occupational accidents for 1,000 employees, whereas the frequency rate is the number of occupational accidents (work halted for more than one day) that occurred over a period of 12 months by one million hours worked.
Both frequency and rate count the number of times a behavior takes place. Since frequency, f, is 1/T, wave speed, frequency, and wavelength are related by the equation v = f. In contrast to frequency, rate is time-based. Calculating rate and frequency is simpler and more precise.
To learn more about frequency from given link
https://brainly.com/question/14614149
#SPJ4
Problem 5: Consider the circuit diagram depicted in the figure 0.5 Ω R2 2.5 Ω /2 R 1.5Ω 0.5 Ω 50% Part (a) what equation do you get when you apply the loop rule to the loop abcdergha, in terms of the variables in the figure? Grade= 100% Correct Answer Student Final Submission Feedback Correct! 012 R2+ 112 T3 R3 +32-62 0- 1-(Ti +R2) I2+(R3r2)13 2 Grade Summary Deduction for Final Submissi Deductions for Incorrect Submissions, Hints and Feedback [?] Student Grade-100-0-0-100% 0% 0% on Submission History All Date times are displayed in Central Standard Time Red submission date times indicate late work. Date Time 9:25 PM Answer Hints Feedback 1 Oct 29,2018 0- 1-(Ti +R2) I2+(R3r2)13 2 50% Part (b) If the current through the top branch is 12-0.505 A, what is the current through the bottom, 13, in amps?
Part(a) The equation for the loop is 0 −1−(R1 +R2)I2+(R3+R2)I3=0
Part(b) The current through the bottom branch 13 is 0.75 A.
(a) This equation is found by applying the loop rule, which states that the sum of voltage drops around a loop is equal to zero. To find the equation, we start at the point, and move clockwise around the loop. At each point, we add the voltage drop of the component connected between that point and the previous point. We then substitute the component values into the equation.
For example, the voltage drop across R1 is equal to I2 * R1. In this equation, I2 and I3 are the currents through R2 and R3 respectively.
(b) To calculate this, we need to use Ohm's Law, which states that the voltage across a resistor is equal to the current through the resistor multiplied by the resistance.
First, we need to calculate the total resistance of the circuit.
R total = R_1 + (1/2)*R_2 + R_3
= 0.5 + (1/2)*2.5 + 0.5
= 2.5 Ω
Now, we can use Ohm's Law to calculate the current through the bottom branch.
I 13 = V/R
= (12-0.5)/2.5
= 0.75 A
Therefore, the current through the bottom branch 13 is 0.75 A.
To learn about Ohm's Law:
brainly.com/question/14296509
#SPJ4
Consider the fictional case of the incredible shrinking man. if he shrinks proportionately to 1/10 his original height, his weight will be multiplied by question? 0.1 0.001 0.0001 0.01
The final weight will be reduced by 0.1 of its original weight.
Equation modelling is the process of writing a mathematical verbal expression in the form of a mathematical expression for correct analysis, observations and results of the given problem.
A mathematical expression is made up of terms(constants and variables) separated by mathematical operators.
A mathematical equation is used to equate two expressions.
Given that, fictional shrinking man shrinks proportionately to 1/10 th of his original height.
Let, weight be W.
W = mg
m = ρ V
Then W = ρ V g
Assume the body to be cylinder of radius r and height h, we can write,
W = π r²ρ g h
So, the initial weight is W = π r²ρ g h
After shrinking W becomes W'.
W' = π r²ρ g h/10
Then, W'/W = (π r²ρ g h/10)/π r²ρ g h = 0.1
Thus, the final weight will be reduced by 0.1 of its original weight.
To know more about weights:
https://brainly.com/question/9122811
#SPJ4
A square metal plate 0.180 m on each side is pivoted about an axis through point O at its center and perpendicular to the plate. (See the figure below (Figure 1) .)
Calculate the net torque about this axis due to the three forces shown in the figure if the magnitudes of the forces are F1 = 17.0 N, F2 = 27.0 N, and F3 = 13.0 N. The plate and all forces are in the plane of the page. (N.m)
the answer 1.73 is incorrect
The net torque to that axis due to three forces is 2.554 Nm.
How to calculate the net torque?[tex]F_1[/tex] = forces 1 = 17 N
[tex]F_2[/tex] = forces 2 = 27 N
[tex]F_3[/tex] = forces 3 = 13 N
α = side of metal plate = 0.18 m
Net torque can be calculated by multiple the forces by distance. For the question, the [tex]F_1[/tex] will be negative because the forces of [tex]F_3[/tex] will move the square metal plate to that side.
Net torque = [tex]-F_1\frac{a}{2} + F_2\frac{a}{2} + F_3 sin(45)\frac{a}{2} + F_3 cos(45)\frac{a}{2}[/tex]
= [tex]-17\frac{0.18}{2} + 27\frac{0.18}{2} + 13sin(45)\frac{0.18}{2} + 13 cos(45)\frac{0.18}{2}[/tex]
= -1.53 + 2.43 + 0.827 + 0.827
= 2.554 Nm.
Thus, the net torque for that three forces shown in the figure is 2.554 Nm.
You question is incomplete, but most probably your full question was
(image attached)
Learn more about net torque here:
brainly.com/question/14927912
#SPJ4
How do you find the gravitational force between two objects with the same mass?
The formulation for gravitational force does have the variables F, G, m1, m2, and r2.
The product of something like the gravitational constant as well as the masses of both the two items, divided with the square of such distance separating the two objects, would be the equation for the gravitational force among two things.
The formula is given as:
Force = (Multiplication of g, m ) / square of distance among both the objects.
= F = (G × M × m (mass)) / r²
where,
Force = F
Gravitational Constant = G
Mass of one object = M
Mass of another object = m
Distance = r
Since all of the items in this situation share the same mass, the gravitational force equation is,
F = (G X M X m(mass)) / r² (distance)
Gravitational force was the force utilized by the earth to pull an item toward it. Issacs Newton made the discovery after seeing an apple fall from either the tree.
To know more about Gravitational Force:
brainly.com/question/1633884
#SPJ4
The half-life of a radioactive substance with the decay rate shown in the graph above is closest to
(A) 3 seconds
(B) 7 seconds
(C) 14 seconds
(D) 18 seconds
(E) 21 seconds
The half life of the sample is obtained as 21 seconds. Option E.
What is the half life?We know that the half life is the time that is taken for only half of the radioactive materials that was initially present to remain. We know that the material would have to be radioactive thus it would disintegrate as time passes.
Looking at the graph we can see that the half life can be traced from the graph that has been shown in the image that has been attached to this answer. The half life of the system is 21 seconds.
Learn more about half life:https://brainly.com/question/24710827
#SPJ1
What does the II next to an element mean?
The II next to elements represent the number of atoms which are joined together for forming a molecule.
The Roman numeral (II) if written next to an element then it denotes the oxidation state of the ion.
Let us assume that,
We need to represent the two atoms of an element Nitrogen, we can either denote it by writing NN or we can simply write N2.
Here 2 which is written in the subscript of an atoms denotes that for forming N2 two atoms of Nitrogens are used.
In some places, Roman numerals are also used.
In Chemistry Roman numerals like (I, II. III etc) are used for denoting the charge and the oxidation state of the transition metal ion.
Some common examples are Fe2+ and Fe3+.
For more such questions on Ions:
https://brainly.com/question/13692734
#SPJ4
What is the unit used to measure the frequency of a sound?
Hertz are used to measure frequency (Hz).This refers to the number of pressure waves per second that would pass a fixed place in the case of sound.
What does hertz mean? The hertz unit of frequency (Hz).In the case of sound, this refers to how many pressure waves would pass a fixed spot each second.The amount of vibrations per second that the sound-transmitting particles are producing is also the same.Ten waves would pass a given place in one second during a sound with a frequency of 10 Hz.The term "hertz" refers to a frequency (or change in state or cycle in a sound wave, alternating current, or other cyclical waveform) of one cycle per second.Cycles per second (cps), the previous word, is now obsolete.The pace of current direction changes each second is known as frequency.To learn more about Hertz refer
https://brainly.com/question/254161
#SPJ4
How far above Mercury's surface would a Mercury geosynchronous satellite have to be if Mercury's mass, radius, and period are 3.30 x 1023 kg, 2439.00 km, and 1407.00 hours, respectively?
Answer:
The mass of the satellite is: m=475kg
The height of the satellite from the surface of mercury is: h=265km
The mass of mercury is: M=3.30×1023kg
The radius is: r=2.24×106m
which of these is the correct answer
Answer:
Option A sponge because at the first sponge was not so heavy than other but when it was dipped in the bucket of water for 30 minutes it absorbed the water as it has many holes in it and the density of water is 1000Kg per metre cube the weight of water and sponge was high
if a ball of volume v and density is fully submerged to a depth h in water of density pw. what is the formula for the boyuant force it experiences?
The buoyant force experienced by an object fully submerged in a fluid is given by the formula:
Fb = p * g * Vwhere Fb is the buoyant force, p is the density of the fluid, g is the acceleration due to gravity, and V is the volume of the object.
If you are given the volume and density of the ball and the density of the water, you can use this formula to calculate the buoyant force experienced by the ball. Simply plug in the appropriate values for p (the density of the water), g (the acceleration due to gravity, which is approximately 9.81 m/s^2 on Earth), and V (the volume of the ball).
It's important to note that this formula only applies to objects that are fully submerged in the fluid. If the object is partially submerged, the buoyant force will be less than what is calculated using this formula. In this case, you would need to take into account the volume of the object that is submerged in the fluid in order to calculate the buoyant force accurately.
Learn more about Boyuant Force here:
https://brainly.com/question/11884584
#SPJ4
astronomers detect a gas giant exoplanet orbiting its host star on an eccentric orbit with a semimajor axis of 100 au. this provides evidence for:
The detection of a gas giant exoplanet orbiting its host star on an eccentric orbit with a semimajor axis of 100 au (astronomical units) could provide evidence for a number of things, depending on the specifics of the system.
Here are a few possibilities:
The presence of a distant, unseen companion: If the gas giant's orbit is highly eccentric (meaning it is more oval-shaped than circular), this could indicate the presence of a companion object, such as another planet or a brown dwarf, that is gravitationally interacting with the gas giant and influencing its orbit.
The influence of other planets: If the gas giant is not the only planet in the system and there are other planets with more modest orbits, their combined gravitational influence could be shaping the gas giant's orbit.
The presence of a primordial disk: A gas giant orbiting at such a great distance from its host star could have formed in a primordial disk of gas and dust that surrounded the star in its early stages of development.
The presence of a "rogue" planet: It is also possible that the gas giant is a "rogue" planet, meaning it is not orbiting a star at all, but rather is floating freely through the galaxy. However, this is less likely given the presence of an eccentric orbit, which suggests the presence of a gravitational influence.
Learn more about Planets here:
https://brainly.com/question/1286910
#SPJ4
How long will it take for a 40.0 gram sample of I 131 half-life 8.040 days to decay to 1 100 its original mass?
It will decompose to 1/100 of its initial mass in 53.4 days.
How long before half of a sample of 131i decays?A radioisotope with an 8-day half-life is iodine-131. By emitting beta particles, it decomposes into xenon-131. Any sample of iodine-131 will have lost half of its atoms after eight days, leaving the sample with a composition of 50% iodine-131 and 50% xenon-131.
How is decay rate determined?The deterioration rate is expressed as a percentage. The decimal equivalent can be obtained by simply reducing the percentage and multiplying it by 100. Therefore, it is possible to determine the decay factor b = 1-r. For instance, the exponential function's decay rate is 25% if the rate of decay is 0.25 and b = 1- 0.25 = 0.75 for the decay factor.
To know more about half-life visit:-
https://brainly.com/question/24710827
#SPJ4
What is the equation that shows the inverse relationship between wavelength and frequency?
Answer:
V = f * λ velocity equals frequency * wavelength
If f is increased then λ must decrease for the velocity to remain constant.
What produces radiogenic heat?
Answer:
Radioactive decay accounts for about half of the Earth's internal heat. Due to their enrichment compared with other radioactive isotopes, four radioactive isotopes mainly contribute to radiogenic heat: uranium-238 (238U), uranium-235 (235U), thorium-232 (232Th), and potassium-40 (40K).