Remember the formula
[tex]\\ \rm\Rrightarrow A(t)=A_o(0.5)^{\frac{t}{h}}[/tex]
h is half life[tex]\\ \rm\Rrightarrow A(7.82\times 10)=A(78.2)[/tex]
[tex]\\ \rm\Rrightarrow 4.11\times 10^{76}(0.5)^{\frac{78.2}{3.91\times 10^{5}}}[/tex]
[tex]\\ \rm\Rrightarrow 4.11\times 10^{76}(0.5)^{20\times 10^{-5}}[/tex]
[tex]\\ \rm\Rrightarrow 4.11\times 10^{76}(0.5)^{0.0002}[/tex]
[tex]\\ \rm\Rrightarrow 4.11\times 10^{76}(0.998)[/tex]
[tex]\\ \rm\Rrightarrow 4.10178\times 10^{76}[/tex]
Why no options matched?
That time given in end i.e 7.82×10
10 should contain some power to match our options .The number of nuclei of calcium-47 left after 7.82 x 10⁵s is 1.03 x 10¹⁶.
This can be found out using half life and laws of radioactive disintegration.
What are the laws of radioactive disintegration?
The Law of radioactive disintegration states the number of radioactive decay per unit time is proportional to the number of nuclei present in the sample initially.
So, ΔN/Δt = λN
Where, ΔN = number of radioactive nuclei decayed
Δt = time taken for decay
N = No of nuclei present initially
λ= decay constant
What is Half life?Half life is the time taken for the radioactive nuclei to reach half of its initial value.
Half life is given by
[tex]t_{1/2}[/tex] = λ/t
Given here, [tex]t_{1/2}[/tex] = 3/91 x 10.⁵s
N = 4.11 x 10¹⁶.
t = 7.82 x 10.⁵s
We see here that t = 2([tex]t_{1/2}[/tex])
Now, number of radioactive nuclei left undecayed in one half life is N/2
So number of nuclei left undecayed in 2 half lives will be 1/2(N/2) = N/4
So number of nuclei left in the sample will be N/4 = (4.11 x 10¹⁶.)/4
So Number of nuclei left in the sample = 1.03 x 10¹⁶.
Hence 1.03 x 10¹⁶is the correct answer.
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the following are three frequencies of sound wave:
1800Hz,50Hz,10,000Hz.
a).which has the highest pitch and which has the lowest pitch?
b).what does Hz stands for?
sound travels faster in air if the air temperature is:
A force applied to a spring compresses the spring 11 cm, storing a certain amount of elastic potential energy. Then a larger force is applied to compress the spring a total of 66 cm. How does the elastic potential energy stored in the spring after it is compressed 66 cm compare to the elastic potential energy stored in the spring after it was compressed 11 cm
Let k be the spring constant.
• When the spring is compressed by 11 cm = 0.11 m, it stores
1/2 k (0.11 m)²
of potential energy.
• When it's compressed by 66 cm = 0.66 m, it stores
1/2 k (0.66 m)²
of potential energy.
Then the ratio of these potential energies is
(1/2 k (0.66 m)²) / (1/2 k (0.11 m)²) = 36
which is to say, the spring stores 36 times more energy when it's compressed by 66 cm compared to 11 cm.
Describe the electric and magnetic fields of an electromagnetic wave.
Fill in the blanks in the following paragraph to correctly identify phenomena that help provide evidence for the particle nature of light
An electron absorbs energy and emits electromagnetic radiation based on its transition.
What is an Electron?This is defined as a sub-atomic particle which has a negative charge. It's involved in a chemical reaction which results in the formation of new substances.
Classical physics predicted that at a high enough temperature, ultraviolet light would be emitted. instead white light was emitted resulting in the ultraviolet radiation.
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what is collinear and concurrent
Answer:
Collinear Force System: When the lines of action of all the forces of a system act along the same line, this force system is called collinear force system. Concurrent Force System: The forces when extended pass through a single point and the point is called point of concurrency.
A common practice for a person with a high fever is to take a bath in cool water. Assuming an 80 kg person is really ill and needs to cool down from 40°C to 37°C. What is the minimum amount of water needed for bathing assuming the water begins at room temperature, 25°C?
The minimum amount of water needed for bathing assuming the water begins at room temperature is 16.58kg.
What is thermal equilibrium?When two bodies at different temperature come into contact, they share the heat through conduction. After some time, temperature of both becomes equal. This condition is said to be a body in thermal equilibrium with other.
Heat gained by the water = heat lost by the ill person
m x Cw x ΔT = M x Cp x Δt
where, mass of person M = 80kg, Cp =specific heat of body =3470, specific heat of water Cw= 4186, then mass of water m will be
m x 4186 x (37-25) =- 80 x 3470 x (37-40)
m = 16.58kg
Thus, the mass of water needed is 16.58kg.
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A 12 v battery produces a current of 25 amps. What is the resistance
Please help me
Answer:
The resistance is 2 ohms
The brightness of a star decreases by the square of the distance. This is known as:.
Answer:
inverse-square law.
Explanation:
Since the area increases as the square of the distance, the brightness of the light must decrease as the inverse square of the distance.
hope this helped you!
Can someone please answer this, ill give you brainliest Would be very appreciated.
A decrease in the ice caps causes a(n) (options decrease, increase) in the absorption of sunlight. This causes the global temperature to (options rise, fall) causing more ice caps to melt. As more ice caps melt, the temperature (options rises, falls). This is an example of a (options negative, positive) feedback loop.
Answer:
See below ~
Explanation:
A decrease in the ice caps causes a(n) increase in the absorption of sunlight. This cause the global temperature to rise causing more ice caps to melt. As more ice caps melt, the temperature rises. This is an example of a negative feedback loop.
A decrease in the ice caps causes a(n) increase in the absorption of sunlight. This causes the global temperature to rise causing more ice caps to melt. As more ice caps melt, the temperature rises. This is an example of a negative feedback loop.
The options are followed by
IncreaseRiserisesnegativeBefore you start your engine, __________ A. adjust the seat so you can reach all controls. B. make sure your car is in reverse or neutral gear before starting the engine. C. move your car before you have looked in front, behind and to the side for pedestrians and oncoming traffic. D. all of the above
Answer:
A. adjust the seat so you can reach all controls
------------------------------------------------------
This is so you can reach the gas petal, break petal, steering wheel, (and other things) easier so you won't have to lean forward and it makes it easier for when you're driving. Especially if you need to quickly press your breaks, you'll be able to do this a lot faster if you're closer to them than if you had to reach in order to do so.
I hope this helped, im not the best at explaining things lol
Assuming we receive a signal from a civilization on the other side of our galaxy, a two-way conversation with them is ________.
What is the voltage in a cirucit with a current of 3.0 amps and a resistance of 2.0 Ohms?
Answer:
6 v
Explanation:
V = IR
= 3 A * 2 ohm = 6 v
HELP PLEASE
Which is true about the price of sustainable buildings?
It is generally less expensive over the lifetime of the building, due to lower energy costs in production of the materials and lower energy bills,
It is almost always less expensive upfront because insulation is so inexpensive.
It is almost always more expensive, but businesses choose to construct them anyway because climate change is a priority for them.
It is generally more expensive over the lifetime of the building, which is an issue that should be weighed in a cost-benefit analysis.
Sustainable buildings are generally less expensive over the lifetime of the building, due to lower energy costs in production of the materials and lower energy bills. Option A is correct.
What is sustainable buildings?Sustainable buildings refer to both a structure and the implementation of environmentally responsible and resource-efficient methods.
Sustainable buildings are generally less expensive over the lifetime of the building, due to lower energy costs in production of the materials and lower energy bills,
Hence,option A is correct.
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Match each space mission with the correct milestone.
1. first animal in space
Apollo 11
2. first person in space
Sputnik 2
3. first person on the moon
Salyut
4. first man-made object in space
Vostok 1
5. first American in space
Sputnik 1
6. first space station
Freedom 7
Matching each space mission with the correct milestone
First animal in space ____________ Sputnik 2first person in space ____________ Vostok 1first person on the moon _________ Apollo 11first man-made object in space ____ Sputnik 1first American in space __________ Freedom 7 first space station ______________ SalyutMeaning of space missionA space mission is a mission that takes an individual, animal, a thing or material out of earth using a spaceship. This mission is always carried out with a desire to find out more about the galaxy earth is a member of and to learn about other planets.
In conclusion, the list above is the accurate Matching of each space mission with the correct milestone.
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Answer:
See attachment below, Hope it helps!
NEED HELP ASAP WILL GIVE 20 POINTS
Floods are natural disasters that can cause what other natural disaster?
tsunami
landslide
hurricane
erosion
please help me with the question below the best answer with an explanation will get brainliest
Answer:
B
Explanation:
i hope this is correct.
what could you do to increase the final momentum of a golf ball?
Answer:
I would hit it as hard as you can with the club.
Explanation:
well one thing that I like to do is hit the golf ball as hard as possible with the club.
This is because for me, when I do that, I can normally get more momentum which means I also get a farther hit.
Line segment gj is a diameter of circle l. angle k measures (4x 6)°. circle l is inscribed with triangle g j k. line segment g j is a diameter. line segments g k and k j are secants. angle k has a measure of (4 x 6) degrees. what is the value of x? 21 24 32 44
The value of x in the given right triangle in a semicircle is determined as 21.
What is the measure of a triangle in a semicircle?The triangle in a semicircle is always a right angle triangle.
From the figure shown, we can say that the triangle G J K is right triangle and m<K = 90degrees.
Given that m<K = 4x + 6, we will can use the following equation to find the value of x as shown:
4x + 6 = 90
4x = 90 - 6
4x = 84
x = 21
Thus, the value of x in the given right triangle in a semicircle is determined as 21.
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[tex] \large\textbf{Question } [/tex]~
[tex] \textsf{How many images will be formed when two plane } [/tex][tex] \textsf{mirrors are inclined on each other by an angle of 60° ?} [/tex]
[tex] \texttt{[ Need explanation ]} [/tex]
[tex] \bold{\underline{\underline{\underbrace{Answer}}}} [/tex]
5 images
Explanation:
⠀
⠀
⠀⠀⠀⠀▦ NoteWhat is reflection of light?
The reflection of light is the phenomenon in which the rays of light falls on the object and change it's path.
⠀
How image is formed in plane mirror?
When you look at the mirror the image is formed behind the mirror and it is virtual. The light from the object which reaches the mirror gets reflected back.
⠀
⠀
⠀⠀⠀⠀SolutionThe formula to find the no. of images between the 2 plane mirror at any angle θ.
[tex] \sf No. \: of \: images = \frac{360 \degree}{ \theta} - 1[/tex]
According to the question the plane mirror is inclined at 60° angle.
Substituting the required values.
[tex] \sf \large \frac{ \cancel{360} \small \: \: 6}{ \cancel{60}} - 1 \\ \\ \sf \large 6 - 1 \\ \\ \boxed{ \frak{ \implies 5} }[/tex]
The 2 plane mirror will form 5 images inclined at 60° angle.
help me, i don't know the answer
Explanation:
1)
A) Bb BB
B) 50%
2)
A) 50%
B) b. b
B. Bb. Bb
b. bb. bb
Show that the square of the period of revolution of a satellite is directly proportional to the cube of the orbital radius
Answer:
Explanation:
50 POINTS! I PROMISE BRAINLIEST IF PLEASEEE I NEED HELP!
Station A
? Arrival Time for P Wave
minu
? Arrival Time for 5 Wave
? S-P Lag Time (secs)
? Distance from Epicenter (km)
30
Station B
TIME(econd
Station B
? Arrival Time for P Wave
wwwwwwww
? Arrival Time for S Wave
? S-P Lag Time (secs)
? Distance from Epicenter (km)
30
TIME (second)
-Buon C
Station C
? Arrival Time for P Wave
10
призми мили
? Arrival Time for S Wave
? S-P Lag Time (secs)
100
300
200
Distance from Epicenter
? Distance from Epicenter (km)
90
TIME (second)
NOW: Use your information above to determine which earthquake these seismographs represent. Check the correct box!
90
2
8
8
*PART THREE:
MYSTERY EARTHQUAKE
/Mark the start of the P Wave AND S Wave
Find the Lag Time
Use the Lag Time Graph to determine each
Stations' distance to the epicenter.
Based on the Distances, choose which map
depicts your earthquake!
Graph
Lag time of S-wave behind P-wave
(seconds)
100 0
8
Nasme
8
IF THE CAPACITOR HAS PLATE AREA OF 0.2m² AND DISTANCE BETWEEN THEM IS 0.04 m. What is the capacitance if dielectric constant is E=0.001 C/VM.
please i need it hurry if correct mark u brainliest.please hurry.
[tex]\\ \rm\Rrightarrow C=\dfrac{\epsilon_oA}{d}[/tex]
[tex]\\ \rm\Rrightarrow C=\dfrac{0.2(0.001)}{0.04}[/tex]
[tex]\\ \rm\Rrightarrow C=\dfrac{0.0002}{0.04}[/tex]
[tex]\\ \rm\Rrightarrow C=0.005F[/tex]
[tex]\\ \rm\Rrightarrow C=5mF[/tex]
Explanation:
Given data :
Given data :Plate area = 0.2m^2
Given data :Plate area = 0.2m^2Distance between plates=0.04m
Given data :Plate area = 0.2m^2Distance between plates=0.04mdielectric constant = 0.001 C/vm
Given data :Plate area = 0.2m^2Distance between plates=0.04mdielectric constant = 0.001 C/vmRTF=Capacitance.
Given data :Plate area = 0.2m^2Distance between plates=0.04mdielectric constant = 0.001 C/vmRTF=Capacitance. SolutionGiven data :Plate area = 0.2m^2Distance between plates=0.04mdielectric constant = 0.001 C/vmRTF=Capacitance. SolutionFirst formula for capacitance .
C= E A/ DC= 0.001 × 0.2 0.04C = 0.0002 0.04C = 0.005 FC = 5mF
What are the functions of the respiratory system?
Answer:
- Allows you to talk and to smell.
- Warms air to match your body temperature and moisturizes it to the humidity level your body needs.
- Delivers oxygen to the cells in your body.
- Removes waste gases, including carbon dioxide, from the body when you exhale.
- Protects your airways from harmful substances and irritants
What might you look for as evidence that fusion occurs inside a star?
Answer: neutrinos
Explanation:
calculate area triangle 15*20
Answer:
300
Explanation:
15 * 20 = 30
15 *
20 =
——
300
you are designing an airport for small planes. one kind of airplane that might use this airfield must reach a speed before takeoff of at least 27.8m/s and can accelerate at 2.00m/s a)if the runway is 150m long,can this airplane reach the required speed for take off?(in this case v=24.5 m/s) b) if not, what minimum length must the runway have(193m)
(a)The required speed for take off will be 24.49 m/sec.
(b)The minimum length must the runway have 193 m.
What is speed?Speed is defined as the rate of change of the distance or the height attained. it is a time-based quantity. it is denoted by u for the initial speed while v for the final speed. its SI unit is m/sec.
(a)The required speed for take off will be 24.49 m/sec.
From the Newtons third equation of motion;
[tex]\rm v^2 = u^2+2as \\\\ v=0+2 \times 2 \times 150 \\\\ v=\sqrt{600}\\\\ v=24.49 \ m/sec[/tex]
Hence, the required speed for take off will be 24.49 m/sec.
(b)The minimum length must the runway have 193 m.
From the Newtons third equation of motion;
[tex]\rm v^2 = u^2+2as \\\\ (27.78)^2 = 0+2\times 2 s \\\\\ s=192.93 \ m[/tex]
Hence, the minimum length must the runway have 193 m.
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Identify the products of this single-replacement reaction between sulfuric acid and aluminum. Then balance the equation
___H2SO4 + ___Al → ___ + ___
Answer/Solution
I hope it help.
Aluminium is far powerful and reactive than hydrogen so it will displace H_2 easily.
The reaction becomes
H_2SO_4+Al—»Al_2(SO_4)_3+H_2Balanced reaction
3H_2SO_4+2Al—»Al_2(SO_4)_3+3H_2