Answer:
It is conserved
Explanation:
A freshly prepared sample of radioactive isotope has an activity of 10 mCi. After 4 hours, its activity is 8 mCi. Find: (a) the decay constant and half-life T1/2; (b) How many atoms of the isotope were contained in the freshly prepared sample? (c) What is the sample's activity 30 hours after it is prepared?
Answer:
(a). The decay constant is [tex]1.55\times10^{-5}\ s^{-1}[/tex]
The half life is 11.3 hr.
(b). The value of N₀ is [tex]2.38\times10^{11}\ nuclei[/tex]
(c). The sample's activity is 1.87 mCi.
Explanation:
Given that,
Activity [tex]R_{0}=10\ mCi[/tex]
Time [tex]t_{1}=4\ hours[/tex]
Activity R= 8 mCi
(a). We need to calculate the decay constant
Using formula of activity
[tex]R=R_{0}e^{-\lambda t}[/tex]
[tex]\lambda=\dfrac{1}{t}ln(\dfrac{R_{0}}{R})[/tex]
Put the value into the formula
[tex]\lambda=\dfrac{1}{4\times3600}ln(\dfrac{10}{8})[/tex]
[tex]\lambda=0.0000154\ s^{-1}[/tex]
[tex]\lambda=1.55\times10^{-5}\ s^{-1}[/tex]
We need to calculate the half life
Using formula of half life
[tex]T_{\dfrac{1}{2}}=\dfrac{ln(2)}{\lambda}[/tex]
Put the value into the formula
[tex]T_{\dfrac{1}{2}}=\dfrac{ln(2)}{1.55\times10^{-5}}[/tex]
[tex]T_{\dfrac{1}{2}}=44.719\times10^{3}\ s[/tex]
[tex]T_{\dfrac{1}{2}}=11.3\ hr[/tex]
(b). We need to calculate the value of N₀
Using formula of [tex]N_{0}[/tex]
[tex]N_{0}=\dfrac{3.70\times10^{6}}{\lambda}[/tex]
Put the value into the formula
[tex]N_{0}=\dfrac{3.70\times10^{6}}{1.55\times10^{-5}}[/tex]
[tex]N_{0}=2.38\times10^{11}\ nuclei[/tex]
(c). We need to calculate the sample's activity
Using formula of activity
[tex]R=R_{0}e^{-\lambda\times t}[/tex]
Put the value intyo the formula
[tex]R=10e^{-(1.55\times10^{-5}\times30\times3600)}[/tex]
[tex]R=1.87\ mCi[/tex]
Hence, (a). The decay constant is [tex]1.55\times10^{-5}\ s^{-1}[/tex]
The half life is 11.3 hr.
(b). The value of N₀ is [tex]2.38\times10^{11}\ nuclei[/tex]
(c). The sample's activity is 1.87 mCi.
Which of the following statements about the technique of hypnotic regression is not true?
O Recovered memories are not reliable.
Courts often depend upon recovered memories.
O Memories may be planted by the hypnotist.
The process may create stress for the subject.
Answer:
B. is the correct answer just took the topic review.
Explanation:
Edge2020. Hope that this helps! Peace and Love
Courts often depend upon recovered memories is the wrong statement about the hypnotic regression.
What is hypnotic regression?Hypnotic regression is a contentious method because it can have a number of negative effects on the subjects who undergo it. For the beginners, the memories recovered through any regression can be doubtful and not trust-worthy. All the suggestions or leading questions from the hypnotist or other people of witnesses can affect the memory.
The previous lives memories will be found by the hypnotic technique as a past life regression. If they used to remember the past life by this method they have high chance of getting into the traumas.
Regression therapy mostly used to identify the cause of your current thoughts and reactions. Therapists who is using this techniques to access subconscious memories that are guiding your current behaviour.
Regression therapy is a method of treatment that could approach and focuses on resolving particular past events that are thought to be interfering or relatable with a person's current mental and emotional well-being.
Hence, Option B is the correct answer.
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A car travels at a constant speed of 70 km/hr for 15 minutes. The car decreases its speed from 70 to 40 km/hr over the next two minutes and then continues to travel at a constant speed of 40 km/hr for the next 5 minutes Which of the following graphs best represents the car's motion during the given time period?
Answer:
A car travels at a constanT
Eclipses occur because the Moon?
A
does not create its own light and only reflects light from the Sun.
o
does not create its own light and only reflects the light from Earth.
o
с
creates its own light, which is blocked by the Sun during an eclipse.
creates its own light, which is blocked by Earth during an eclipse.
Answer:
с
creates its own light, which is blocked by the Sun during an eclipse.
Explanation:
might not be right but its what i remember
Which words help you to determine the meaning of the word decelerate in paragraph 3
Answer:
the words
Explanation:
Answer:
Pressing the brake pedal
Explanation:
Decelerate sounds a lot like the word accelerate, but we know that the speed is decreasing, so it would have to be going down, getting slower, so whichever sounds like a good example of speed decreasing should be a good answer!
The photo shows dew drops that formed on the grass when temperatures
cooled during the night. Which change of state happened to form the dew?
A. Liquid to gas
B. Gas to liquid
C. Solid to gas
D. Gas to solid
please help
Which equipment is best to hold and to measure liquids?
A). flask and graduated cylinder
B). scale and ruler
C). caliper and thermometer
D). stopwatch and beaker
Answer:
I'm pretty sure that the answer is A
An ant is crawling along a yardstick that is pointed with the 0-inch mark to the east and the 36-inch mark to the west. It starts at the 14-inch mark, crawls to the 20-inch mark, then moves to the 16-inch mark. What was the total distance the ant traveled?
Given :
An ant is crawling along a yardstick that is pointed with the 0-inch mark to the east and the 36-inch mark to the west.
It starts at the 14-inch mark, crawls to the 20-inch mark, then moves to the 16-inch mark.
To Find :
The total distance the ant traveled.
Solution :
Total distance travelled by ant = (distance between 14 and 20 inch mark) +
(distance between 20 and 16 inch mark)
Total distance = (20-14 ) + ( 20-16) = 6 + 4 = 10 inch.
Therefore, total distance the ant traveled is 10 inch.
Hence, this is the required solution.
Protons are found only in the atomic nucleus.
TRUE
FALSE
Answer:
true
Explanation:
Protons and neutrons are found in the nucleus
Dos pilotos suicidas, que están inicialmente a una distancia de 500 m entre sí, deciden chocar directamente de frente arrancando ambos desde el reposo. Ambos autos pueden desarrollar una aceleración máxima constante de 15 m/s2 . Si el piloto A arranca un segundo antes que el piloto B, encuentra: a) la posición donde los autos chocan, medida a partir de la posición donde arranca el piloto A, y b) la rapidez relativa de la colisión (la rapidez de B con respecto a A justo antes de la colisión, ó viceversa).
Answer:
a) El punto de colisión de los dos automóviles desde donde parte el conductor del automóvil A es de aproximadamente 293,14 metros.
b) La velocidad del automóvil A, en relación con la velocidad del automóvil B, es de 15 m / s
Explanation:
Los parámetros del movimiento son;
La distancia entre ambos coches = 500 m
La aceleración de ambos coches = 15 m / s²
La dirección de movimiento de ambos coches = uno hacia el otro
La hora de inicio del conductor A = Un segundo antes de la hora de inicio del conductor B
Por lo tanto, de la ecuación de movimiento, tenemos;
s = u · t + 1/2 · a · t²
v² = u² + 2 · a · s
Dónde;
u = La velocidad inicial de los autos = 0 (los autos parten del reposo)
t = El tiempo de movimiento de una aceleración dada
a = La aceleración = 15 m / s²
s = La distancia recorrida en el tiempo t
Por lo tanto, para el controlador A, tenemos;
s₁ = 0 × (t + 1) + 1/2 × 15 × (t + 1) ² = 7.5 × (t + 1) ²
s₁ = 7.5 × (t + 1) ²
Para el conductor B, tenemos;
s₂ = 0 × t + 1/2 × 15 × t² = 7.5 × t²
s₂ = 7,5 × t²
Dado que ambos chocan a lo largo del camino de 500 m, tenemos;
s₁ + s₂ = 500 metros
∴ 7.5 × (t + 1) ² + 7.5 × t² = 500
∵ s₁ + s₂ = 7.5 × (t + 1) ² + 7.5 × t²
Lo que da;
15 · t² + 15 · t + 7.5 = 500
15 · t² + 15 · t - 492,5 = 0
Resolver usando la aplicación en línea da; t = -6,25181 o t = 5,25181
Dado que t es un número natural, tenemos el valor correcto para t = 5.25181 segundos
a) Por tanto, el punto de colisión de los dos coches desde donde parte el conductor del coche A es;
s₁ = 7.5 × (t + 1) ² = 7.5 × (5.25181 + 1) ² ≈ 293.14 metros
El punto de colisión de los dos automóviles desde donde parte el conductor del automóvil A ≈ 293,14 metros
b) La semilla de A en el punto de colisión se da de la siguiente manera
Velocidad, v₁ = u + a × (t + 1) = 0 + 15 × (5.25181 + 1) ≈ 93.78
v₁ ≈ 93,78 m / s
La semilla de B en el punto de colisión también se da de la siguiente manera
Velocidad, v = u + a × (t) = 0 + 15 × 5.25181 ≈ 78.78
v₁ ≈ 78,78 m / s
Por lo tanto, la velocidad del automóvil A, en relación con la velocidad del automóvil B, [tex]v_{relative}[/tex] se da como sigue;
= v₁ - v₂ = 93,78 m / s - 78,78 m / s = 15 m / s
la velocidad del automóvil A, relativa a la velocidad del automóvil B = 15 m/s.
which one of the following is a derived Si unit a. Newton, b. Meter, c. Mole, d. Kiogram
Answer:
The SI is founded on seven SI base units for seven base quantities assumed to ... The SI derived units for these derived quantities are obtained from these ... mass density, kilogram per cubic meter, kg/m3 ... amount-of-substance concentration, mole per cubic meter, mol/m3 ... solid angle, steradian (a), sr (c), -, m2·m-2 = 1 (b).
Kilogram is a derived SI unit of the following.
Thus, A universal standard for expressing the magnitudes or quantities of significant natural events is the International System of Units.
The acronym SI, which derives from the French term Systèm international stands for the System of Units, also known as the metric system. The meter-kilogram-second (MKS) system, an earlier unit of measurement, serves as the foundation for the SI standard.
The SI standard is promoted and explained by the Bureau international des poids et mesures (BIPM). The organization was founded in 1875 and is known as the International Bureau of Weights and Measures in English. It is governed by the International Committee for Weights and Measures (CIPM).
Thus, Kilogram is a derived SI unit of the following.
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List out Units For: Acceleration
Unit for Acceleration is m/s² or ms raised to -2
Will was riding his bike when a dog ran out in front of him. He slammed on his brakes. During this quick stop, some of the mechanical energy (his motion) was changed into
A) heat energy.
B) light energy.
C) kinetic energy.
D) gravitational energy.
Answer:
A
Explanation:
big brain
During this quick stop, some of the mechanical energy (his motion) was changed into heat energy.
What is energy?Energy is the ability to do work. There are different types of energy such as Heat energy, light energy, kinetic energy, and gravitational energy.
Heat is the energy that moves from one body to another when temperatures are different. Heat passes from the hotter to the colder body when two bodies with differing temperatures are brought together.
The joule is a unit of energy that serves as the SI unit for heat (J). The calorie (cal), which is defined as "the amount of heat necessary to raise the temperature of one gram of water from 14.5 degrees Celsius to 15.5 degrees Celsius," is another common unit of heat measurement.
Therefore, During this quick stop, some of the mechanical energy (his motion) was changed into heat energy.
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Define what velocity means.
Answer:
The velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time. Velocity is equivalent to a specification of an object's speed and direction of motion (e.g. 60 km/h to the north).
Lucy and JoJo need to make 140 cupcakes for the school dance. Lucy made 35 of the cupcakes. JoJo made 42 cupcakes What fraction of the cupcakes do Lucy and JoJo still need to make?
Answer:
9/20
Explanation:
According to this question, Lucy and JoJo need to make 140 cupcakes for the school dance. Lucy made 35 of the cupcakes while JoJo made 42 cupcakes. This means that in total, (42 + 35) cupcakes has been made by both Lucy and JoJo
That is, 77 cupcakes out of 140 has been made. This is 77/140 i.e. 11/20
Since 77/140 cupcakes has been made, Lucy and JoJo still need to make;
140 - 77 = 63 cupcakes to meet up their target for the school dance.
This means that the fraction left is 63/140
63/140 in its lowest term is 9/20
Hence, 9/20 of the cupcakes still need to be made by Lucy and JoJo.
Explanation: 140 - 35 = 105 - 42 = 63
yare yare daze
I use tusk act 4 main
What the meaning of centerpiece
Answer:
1 : an object occupying a central position especially : an adornment in the center of a table. 2 : one that is of central importance or interest in a larger whole the centerpiece of a political agenda.
Explanation:
What type of bond is shown in the figure?
Answer:
ionic
Explanation:
Question 4 of 20
Luke wraps a magnetized steel nail with several coils of insulated wire and
then connects the loose ends of the wire to a 10 W lightbulb. Which step
could he take next to get the lightbulb to light up?
O A. Replace the magnetized nail with a nonmagnetic metal to cause
an electric current to flow in the wire.
O B. Remove the magnetized nail from the wire coil to induce a
magnetic field that will flow through the wire.
C. Move the magnetized nail back and forth within the wire coil to
induce an electric current in the wire.
D. Add several more coils of the wire around the magnetized nail to
make a stronger electric current.
SUBMIT
Answer:
C. Move the magnetized nail back and forth within the wire coil to induce an electric current in the wire.
Hope this helps.
protons are present in sodium atom.
a 11
b 10
C 12
d 9
11
Explanation:
There are 11 protons in a sodium atom
How are velocity, wavelength, and frequency related
Answer:
The wave velocity and the wavelength are related to the wave's frequency and period by vw=λT or vw=fλ. The time for one complete wave cycle is the period T. The number of waves per unit time is the frequency ƒ. The wave frequency and the period are inversely related to one another.
Explanation:
A force of 75 N at an angle of 15° to the direction of motion moves a chair 3 m. Which change would result in more work being done on the chair?
Answer:
Decreasing the angle to 10
Explanation:
Edge 2020
Which model of the atom has electrons traveling in specific paths around the nucleus? Bohr's model Rutherford's model Thomson's model Dalton's model
Answer:
A, Bohr's model
Explanation:
Took the quiz, hope it's right for you.
(The other three did have something to do with it they just didn't create that specific model)
The model of the atom that has electrons traveling in specific paths around the nucleus is Rutherford's model.
Therefore, the correct answer is option B
J. J Thomson proposed that the atom is a sphere of positively charged matter in which negatively charged electron are embedded.
In Rutherford's model of atomic structure, the electrons moves in orbits by electrostatic attraction to the positively charged nucleus.
According to Dalton's atomic theory, atom were indestructible and indivisible solid particle.
Bohr's model made assumption that electron can only exist in circular orbits of definite quantum energy.
According to the question, the model of the atom that has electrons traveling in specific paths around the nucleus is Rutherford's model.
Therefore, the correct answer is option B
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#7 If the Moon’s mass was suddenly tripled, what would occur to the gravitational force between the Earth and the Moon?
(A) Gravitational force would increase by a factor of 3.
(B) Gravitational force would decrease by a factor of 3.
(C) Gravitational force would increase by a factor of 9.
(D) Gravitational force would decrease by a factor of 9.
Answer:
well it would be (A) Gravitational force would increase by a factor of 3.
Explanation:
because the moon is the only thing that gained mass not the Earth
If a racer maintained a constant speed, during which sections of the race would the racer's velocity be the same?
Sections 1 and 2
Sections 2 and 3
Sections 2 and 4
Sections 3 and 4
pls help!!
Answer:
Sections 3 and 4
Explanation:
The correct answer would be sections 3 and 4.
The velocity of an object is the speed of the object in a particular direction. In this case, the speed of the racer is constant irrespective of the distance or the direction. Hence, the sections of the race during which the racer's velocity would be the same would be the sections in which the racer faces the same direction - which is sections 3 and 4.
Find the resultant of an easterly force of 100 N and a southeast force of 80 N acting at 65 degrees to the 100 N force
Answer:
Resultant is 152 N at 28.5 degrees south to the 100 N force
Explanation:
why are force and velocity different?
Answer: If you apply force to an object the velocity changes. But it doesn't work the other way around apply velocity and the force (no!) Velocity does not change on an object. A force pushes or pulls on an object, but velocity is simply something an object has I hope this makes sense to you. Hope this helps :)
Explanation:
PLEASE HELP THIS IS DUE IN 10 MINUTES- (15 points!)
1st question- what are the weather fronts(use the pic for help)
2nd question- who has better weather— high pressure systems or low pressure systems and how do you know?
(Please add explanation)<3
Answer: I would say that B would have better weather because those dots on the right are cold fronts and the smooth side without the dots is a warm front. I hope this helps :)
Explanation:
If an object is moving with constant acceleration, its velocity must
a
change by varying amounts depending on its speed.
b
always decrease.
c
be constant also.
d
change by the same amount each second.
Which event is an example of condensation?
A. Wet clothes are drying on a clothesline.
B. A mirror fogs up when someone takes a hot shower.
C. Water drips from an icicle on the edge of a roof.
O D. Rain turns to sleet as it nears the ground.
Answer:
the answer to your question is b a mirror fogs up when someone takes a hot shower.
The process of conversion of gaseous water to its liquid form is called condensation. The fogs formed on the mirror from the hot shower is an example of condensation.
What is condensation?Condensation is the process of cooling up of water vapor to liquid water. Water vapor condenses when it cools. Condensation can be best understood from the reason behind raining.
When water vaporizers from resources and cools from the sky, and the vapor condenses to form liquid droplets. Similarly we can observe water droplets in the window pane due to the similar effect.
The water vapor arises from the hot shower condenses in the atmosphere and forms the drops on the mirror. Therefore, the mirror fogs up by the hot shower is an example of condensation.
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how much force is needed to accelerate 300 kg at a rate of 4 m/s/s
Answer:
1200
Explanation:
Force = Mass x Acceleration
Answer:
[tex]\boxed {\tt 1,200 \ Newtons }[/tex]
Explanation:
Force can be found by multiplying the mass by the acceleration.
[tex]F=m*a[/tex]
The mass is 300 kilograms.
The acceleration is 4 meters per second squared.
[tex]m= 300 \ kg\\a= 4 \ m/s^2[/tex]
Substitute the values into the formula.
[tex]F= 300 \ kg * 4 \ m/s^2[/tex]
Multiply.
[tex]F= 1200 \ kg * m/s^2[/tex]
1 Newton is equal to 1 kilograms meters per second squared, so our current answer of 1200 kg m/s² is equal to 1200 Newtons.
[tex]F= 1200 \ N[/tex]
The force needed is 1,200 Newtons.