half life, for my physics but pretty sure it involves maths. you don’t have to do them all i’m just confused how to work it out.
Answers
I probably don't have to tell you that the other answer is nonsense, but I'll do it all the same, just in case... Half-life is defined as the time it takes for some radioactive substance to decay to half its original amount.
If it takes n half-lives for some substance with a starting amount of A to decay to a final amount of B, then
[tex]B = \dfrac{A}{2^n}[/tex]
1. If the half-life is x, then after 1 half-life, 5000 units of this substance decays to 2500 units. After another half-life, this decays to 1250. After another, this in turn decays to 625.
So 3 half-lives are required.
In terms of the equation above, we solve for n such that
[tex]625 = \dfrac{5000}{2^n} \implies 2^n = 8 \implies n=3[/tex]
since 2³ = 8.
2. Count how many times you halve 15,000 to end up with 3750:
15,000/2 = 7500
7500/2 = 3750
===> 2 half-lives
In other words,
[tex]3750 = \dfrac{15,000}{2^n} \implies 2^n = 4 \implies n=2[/tex]
3. After 1 half-life, you would end up with
12,000/2 = 6000
and after another half-life,
6000/2 = 3000
i.e.
[tex]\dfrac{12,000}{2^2} = \dfrac{12,000}4 = 3000[/tex]
4. After 1 half-life, you have
26,000/2 = 13,000
After 2 half-lives,
13,000/2 = 6500
After 3 half-lives,
6500/2 = 3250
After 4 half-lives,
3250/2 = 1625
i.e.
[tex]\dfrac{26,000}{2^4} = \dfrac{26,000}{16} = 1625[/tex]
5. If the half-life is 3 years, then 15 years = 3 half-lives.
In the last 3 years, 20,000 would have decayed to 10,000.
In the second-to-last 3 years, 40,000 would have decayed to 20,000.
In the first 3 years, 80,000 would have decayed to 40,000.
i.e.
[tex]\dfrac{x}{2^3} = 10,000 \implies x = 8\times10,000 = 80,000[/tex]
Related Questions
WILL GIVE BRAINLIST QUICK!!! How does biodiversity support different varieties of species? (please put short answer)
Answers
PLEASEHELP THANK YOU SM
Answers
Answer:
I belive it would be the first answer choice.
Explanation:
When the Mass is lower, the ball moves faster so it would have more kintetic energy
An observer in the Northern Hemisphere watches the sky for several hours. Due to the motion of Earth, this observer notices that the stars near the north celestial pole appear to move An observer in the Northern Hemisphere watches the sky for several hours. Due to the motion of Earth, this observer notices that the stars near the north celestial pole appear to move from left to right. nearly vertically upward. counter-clockwise around the celestial pole. from right to left.
Answers
Answer:
counter clockwise
Explanation:
The observer in the Northern Hemisphere will notice that the stars near the NCP to move counter-clockwise
Counter - clockwise : The observer will observe this because the earth movement when viewed from the North pole is in a counterclockwise direction, hence the stars will appear to move in an ant-clockwise direction
An aneurism refers to?
a. a blocked blood vessel
b. varicose vein
c. a hole or weakness in an artery
d. plaque development on the inside of artery wall
Answers
Answer:
The correct answer is a blocked blood vessel.
Explanation:
Hope this helped Mark BRAINLIEST!!!
What is the net force in the y-direction?
0 N
25 N
225 N
250 N
Answers
The correct option is (1) 0 N.
Net force in the y direction is 0 if the vector sum of your forces acting in the y direction is zero.The forces acting on an item are balanced when the net force is zero. Two forces that are acting in the same direction cancel one another out. An item will always remain at rest if the forces are out of balance.Formula of net force -
FNet = Fa + Fg + Ff + .............. FN.
Definition of force
The word 'force' has a precise meaning. At this level, it is completely appropriate to describe a force as a push or a pull.
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Which action has more power
Answers
What are 4 physical properties for the bear
Answers
Answer:
A bear normally has a short, thick neck, a rounded head, a pointed muzzle, short ears, and small eyes. Some species have round faces. Bears have poor eyesight, and most have only fair hearing.
Explanation:
Modern Bears are characterized with large body and stocky legs, a long snout, shaggy hair, plantigrade paws with five non-retractile claws and a short tail.
Grizzly bears (Ursus arctos horribilis) have concave faces, a distinctive hump on their shoulders, and long claws about two to four inches long. Both the hump and the claws are traits associated with a grizzly bear's exceptional digging ability. Grizzlies are often dark brown, but can vary from blonde to nearly black.
The brown bear has a slight hump above its shoulder, round ears, a long snout and big paws with long, curved claws that it uses for digging. Unlike the black bear, it can't climb trees. It can weigh between 350-1,500 pounds. When standing on its hind legs it can be up to 5 feet tall.
Hope this helps :)
(I didn't know which type of bear so i did brown bear and grizzly bear)
A(n) _____ is an object that stops
electrons from completing the circuit.
Answers
What is the relationship between potential and kinetic energy and electricity
Answers
Answer:
The primary relationship between the two is their ability to transform into each other. In other words, potential energytransforms into kinetic energy, andkinetic energy converts into potential energy, and then back again.
What happens to the temperature of an air mass as it rises, and why? What happens to the temperature of an air mass as it rises, and why? Temperature increases because fewer air molecules allow the air mass to expand. Temperature decreases because increasing numbers of air molecules allow the mass to expand. Temperature increases because more air molecules force the air mass to contract. Temperature decreases because fewer air molecules allow the air mass to expand. Temperature remains the same because fewer air molecules allow the air mass to expand.
Answers
Answer:
Temperature decreases because fewer air molecules allow the air mass to expand.
Explanation:
Temperature of air mass decreases as it rises . It is so because at upper strata
of atmosphere , air is sparse and therefore air molecules there is relatively less . It results in lower pressure around air mass going up . This results in expansion of gas . Molecules have to do work against mutual attractive force for expansion so their energy becomes less . This cools down the air.
The oxygen side of a water molecule is
Answers
the speed of an electric locomotive is 90kmh .express this speed in m/s with method
Answers
Answer:
24.3 m/s
Explanation:
1 kmh = 0.27 m/s, that makes a conversion ratio of 0.27/1kmh
[tex]\frac{90 kmh}{1}[/tex] x [tex]\frac{0.27 m/s}{1 kmh}[/tex]
The "kmh" n the top and bottom cancel out. And then you just multiply the top 90 x 0.27 and the bottom 1 x 1 to get
[tex]\frac{24.3 m/s}{1}[/tex]
and since its over 1 its just 24.3 m/s
The current of a circuit with a 3.0-volt battery and 1.0 ohm of resistance is __ amps
Answers
Answer:
3 amps
Explanation:
V = IR
I = [tex]\frac{V}{R}[/tex]
I =[tex]\frac{3}{1}[/tex]
I = 3 amps
Two football players with mass 75 kg and 100 kg run directly toward
each other(this means they are running in the opposite directions).
The 75 kg player has a speed of 6m/s to the right and the 100 kg
player has a speed of 8 m/s to the left. What is the momentum of
the 75 kg player?
Answers
Answer:
A. 2 m/s
(m x v) (m x v) = (m+m)v
How much work (MJ) must a car produce to drive 125 miles if an average force of 306 N must be maintained to overcome friction?
Answers
Answer:
The right solution is "61.557 MJ". A further explanation is given below.
Explanation:
The given values are:
Force,
F = 306 N
Drive,
D = 125 miles,
i.e.,
= 201168
meters
As we know,
The work done will be:
= [tex]F\times S[/tex]
On substituting the given values, we get
= [tex]306\times 201168[/tex]
= [tex]61557408 \ J[/tex]
On converting it in "MJ", we get
= [tex]61.557\times 10^6 \ J[/tex]
= [tex]61.557 \ MJ[/tex]
As the north pole of the magnet approaches the solenoid, a current is induced in the solenoid, creating an electromagnet. The end closest to the north pole will be a ____ pole.
Answers
Answer:
south
Explanation:
An electromagnet is a magnet that is formed when a current wire loop is rotated in a magnetic field, a current gets induced in the wire loop. A changing magnetic field causes an electric current in the wire loop.
A solenoid is a wire coil into a wire coil. When a iron piece in placed inside the solenoid it becomes electromagnet.
Since the north pole of a magnet approaches a solenoid, current is induced and the end near the north pole of the magnet becomes the south pole as like poles distract and unlike poles attract.
In a thunderstorm at 32.0°C, Reginald sees a bolt of lightning and hears the thunderclap 2.00s later. How far from Reginald did the lightning strike? The speed of sound through air at 32.0° C is 350.2 m/s.
Answers
Answer:
dont have the answer but you cute
Explanation:
describe what form of electromagnetic radiation does a radio use?
Answers
which type of thermometer is used to measure the temperature of a very hot object and why?
Answers
Answer:
Pyrometer, device for measuring relatively high temperatures, such as are encountered in furnaces. Most pyrometers work by measuring radiation from the body whose temperature is to be measured. Radiation devices have the advantage of not having to touch the material being measured.
Explanation:
Which of the following is NOT a component of skill-related fitness?
A.balance
B.speed
C. Power
D. Heart rate
Answers
Answer:
D
Explanation:
The 1st 3 are important components
sorry for miss spells
A hot air balloon traveled 4 hours at a speed of 200 km/hr. What distance did it travel?
Answers
4 hours * 200 km/hour
200 km to miles: 124.274
4 * 124.274 = 497.096 miles
Where on the periodic table are metal elements most likely found?
A. Along the stairstep line
B. In the main groups
C. On the left side
D. On the right side
Answers
Metal elements are most likely found on the left side of the periodic table. Details about periodic table can be found below.
What is periodic table?Periodic table is a tabular chart of the chemical elements according to their atomic numbers so that elements with similar properties are in the same group or column.
Metallic elements are one of the group of elements found on the periodic table and they include the following:
CalciumPottasiumScandiumMetallic elements are located on the left hand side of the periodic table.
Learn more about periodic table at: https://brainly.com/question/11155928
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Answer: (A) Along the stairstep line
Explanation:
8. List the objects in order from least to greatest inertia
A
B
D
5 kg
4 kg
3 kg
10 kg
a = 1 m/s/s
a 3 m/s/s
a 2 miss
a= 0 m/s/s
Answers
Answer:
mhibyguftyftfrehlknmjhbn
Explanation:
njhvvtfryvbnyuhnuihnjhk
answer this plsss
The range of human hearing is 20 Hz – 20 000 Hz.
Calculate the longest and shortest wavelengths we can hear.
Answers
Explanation:
the velocity of sound in air is 330m/s
and v=fh, where h is wavelength f is frequency,
h=v/f.......(1)
longer wavelength
h=330/20,h=16.5m
shorter wavelength
h=330/20000,h=1.65x10-²m
The lesser frequency was used for finding the longer wavelength since wavelength is inversely proportional to frequency,
thus an increase in frequency brings a decrease in wavelength.
and shorter wavelengths are more high and intense
hope this helps
PLEASE HELPP I NEED TO PASS THIS !!
Answers
Explain what ionisation is and why it is dangerous
Answers
Ionisation: the loss or gain of an electron
It is dangerous because cells that have been ionised can either die, or can mutate incorrectly, which might cause cancer.
People should be more concerned about the global water budget than the local water budget.
True
Answers
Answer:
true
Explanation:
because global helps local
Scenario:
Two marbles role down a hill.
Marble 1 has a mass of 0.2g
Marble 2 has a mass of 1.2g
Marble 1 traveled 22cm in 0.8 seconds
Marble 2 traveled 26cm in 0.8 seconds
Determine the Kinetic Energy involved with each marble
Formulas you will need;
KE = (1/2)mv^2
v=d/t
Answers
Explanation:
K.E. of marble 1 = (1/2) × 0.2 × (22/0.8) ^2
= 0.1 × 756.25
= 75.625
K.E. of marble 2 = (1/2) × 1.2 × (26/0.8)^2
= 0.6 × 1056.25
= 633.75
Having some trouble with this one :/
An object has a kinetic energy of 50 J and a velocity of 5 m/s, what is the mass of the object?
Answers
Answer:
Mass, M = 4 kilograms.
Explanation:
Given the following data;
Kinetic energy = 50 J
Velocity = 5 m/s
To find the mass of the object;
Kinetic energy can be defined as an energy possessed by an object or body due to its motion.
Mathematically, kinetic energy is given by the formula;
[tex] K.E = \frac{1}{2}MV^{2}[/tex]
Where;
K.E represents kinetic energy measured in Joules.
M represents mass measured in kilograms.
V represents velocity measured in metres per seconds square.
Making mass the subject formula;
[tex] M = \frac{2K.E}{V^{2}}[/tex]
Substituting into the equation, we have;
[tex] M = \frac{2*50}{5^{2}}[/tex]
[tex] M = \frac{100}{25}[/tex]
Mass, M = 4 kg
A trampoline spring has a force constant k = 800 N/m and is stretched exactly 17.5cm. What is the energy required to do this?
Answers
Answer:
the energy required for the extension is 12.25 J
Explanation:
Given;
force constant of trampoline spring, k = 800 N/m
extension of trampoline spring, x = 17.5 cm = 0.175 m
The energy required for the extension is calculated as;
E = ¹/₂kx²
E = 0.5 x 800 x 0.175²
E = 12.25 J
Therefore, the energy required for the extension is 12.25 J