If the activity of a source is 70 Bq after 2 years, and 35 Bq after 15 years. How long will be until the activity is 8.75 Bq?​

Answers

Answer 1

Answer:

N = N0 e^-kt          calling k the decay constant

70 = N0 e^-2 kt

35 = N0 e^-15 k

2 = e^(-2 + 15) k

.693 = 13 k

k = .0533

N0 = N e^kt

N0 = 70 e^(.0533 * 2) = 77.87

8.75 = 77.87 e^-(.0533 t)

ln .1124 = -.0533 t

t = -ln .1124 / .0533 = 41 yr


Related Questions

What did Dr Allan McInnes say was required in order to launch a satellite into space, at the necessary altitude and speed? What is required and why?

Answers

Dr Allan McInnes explains why satellites need large rockets to launch them into orbit and why many satellites are launched from near the equator it’s because Satellites need to be placed in orbit high above the Earth’s atmosphere so that the drag of the atmospheric gases doesn’t make the orbiting satellite slow down.

An altitude of 100 km has been adopted by the United Nations as a working definition of where the Earth’s atmosphere ends and space begins.

A driver started from origin and drove 5 km towards east, he then drove 3 km due west. His displacement is:

a. 2 km
b. 8 km towards east
c. 2 km towards east
d. 8 km

Answers

Answer:

c. 2 km towards east

Explanation:

what if water didnt have a negative charge?

Answers

The water molecule, as a whole, has 10 protons and 10 electrons, so it is neutral. ... The unequal sharing of electrons gives the water molecule a slight negative charge near its oxygen atom and a slight positive charge near its hydrogen atoms.

Ok, so the runner then goes from 20m to 11m. Distance? Displacement?

Answers

Answer:

honestly a bit confused by the question, but this would be a 9 meter difference in the distance, moving from 20m to 11m

Explanation:

In a closed system of a cannon and cannonball, which changes would both result in an increase in the kinetic energy of the cannonball when fired from the cannon?

Answers

Answer:

the length of the cannon

the power of the gunpowder

Answer:

i would say B decrease mass of cannon or decrease mass of cannon ball

Explanation:

because when you fire the cannon the cannon ball and powder exit the cannon then that leaves the cannon ball and i would say that the explosion would force it out the cannon but would not increase its mass.

Using Newton’s first law of physics, which explains why it is harder to swim in water with a current (like the ocean) than in contained water (like a pool)?
A.
Perpetual motion can only be interrupted by an unbalanced force.
B.
The current will interfere with perpetual motion more than still water.
C.
It takes much more strength to swim if there is a current than in a pool.
D.
Still water is an immovable object, but currents have their own momentum.

Answers

Answer:

It isn't A.

Explanation:

I got it wrong with the answer A.

it is harder to swim in water with a current (like the ocean) than in contained water (like a pool) because Still water is an immovable object, but currents have their own momentum. The correct option is D.

What is Newton's first law of motion?

Newton's first law of motion, also known as the law of inertia, states that "an object at rest will remain at rest, and an object in motion will remain in motion with a constant velocity unless acted upon by an unbalanced force."

This means that an object will continue to move in a straight line at a constant speed unless an unbalanced force acts upon it. In addition, if an object is at rest, it will remain at rest unless acted upon by an unbalanced force.

The law of inertia can be applied to many situations. For example, if a book is sitting on a table, it will remain at rest until a force is applied to it. Similarly, if a ball is rolling on a flat surface, it will continue to roll at a constant speed in a straight line unless a force, such as friction, slows it down or changes its direction.

This law is fundamental to understanding the behavior of objects in motion, and it forms the basis for the other two laws of motion formulated by Sir Isaac Newton.

Here in the Question,

Swimming in a pool versus swimming in the ocean, the difference lies in the presence of a current in the ocean.

The current in the ocean has its own momentum, and when a swimmer enters the water, they are faced with an additional force that they must overcome to move forward. This means that the swimmer must apply more force and use more energy to overcome the force of the current and move forward in the water.

In still water, on the other hand, there is no external force acting on the swimmer, so they only have to overcome the resistance of the water itself to move forward.

Therefore, The correct answer is D i.e Still water is an immovable object, but currents have their own momentum.

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which type of forces would be experienced by a sled that is being pulled by a rope (choose 4)

Answers

Friction, wind resistance, gravity, tension force

I NEED A 100% ACCURATE ANSWER FOR THIS QUESTION ASAP NO LINKS !!!

Answers

Answer:

The answer is static friction. This is the friction that involves objects that do not move.

Explanation:

Friction is a force which opposes the motion of one object moving relative to another. static friction and kinetic friction are the two type of friction.

Static friction is that type of friction which keeps an object at rest. Force must be applied greater than static friction to move an object. Therefore it is the static friction which helps the pile of rocks from falling apart.

(Brainiest and thanks appreciated)

Answer:

static friction

Explanation:

I did a test like this yesterday same question different object

how does the interstellar medium affect our view of most of the galaxy?

Answers

Answer: It prevents us from seeing most of the galactic disk with visible and ultraviolet light.

(hope this helps) :)

4. A desk with a mass of 10 kg is pushed across a floor with an acceleration of 4 m/s?. What
is the force on the desk? Use the equation F = ma.

Answers

40 N. If you’re using F=MA MxA would be 10x4 which would get you 40 N

Answer:

Below

Explanation:

All we need to do for this question is to plug in our values and solve!

      Force = mass x acceleration

      Force = 10 kg x 4 m/s^2

     Force = 40 Newtons or 40 N

If your teacher requires you to round to sig figs it would be :

    F = 4 x 10^1 N

Hope this helps!

A laser emits a light beam with a wavelength of 630 nm. The jet passes a liquid with a refractive index of 1.3.
What is the wavelength of the light beam in the liquid?

Answers

The wavelength of the laser beam in the liquid is 517 nm

Brainliest?

A shopper walks westward 5.4 meters and then eastward 7.8 meters

Answers

Answer:

13.2 meters

Explanation:

(5.4) + (7.8)

I need help asap please
Will give BRAINLIST for correct answers only
Thank you

A force of 225 N at an angle of 30 degrees to the horizontal displacement. The component of the force that will cause work to be done is?

Answers

Answer:

225cos30

Explanation:

Force in the direction of the work done

225cos30
~~~~~~~~~~~~~

please help!! i’ll mark you the brainliest answer

A box of mass 4kg is being pulled along a rough surface to the right, as shown below. When F=8N, the box accelerates to the right 1m/s^2. If F is doubled to 16N, the acceleration of the box across the same rough surface will be:

A) 1m/s^2
B) 2 m/s^2
C) 3 m/s^2
D) 4 m/s^2
E) 0.5 m/s^2

Answers

Hi there!

Recall that:

∑F = ma

In the given situation, there is acceleration occurring in the horizontal direction, so there is a net force.

∑F = Fa (Force applied) - Fκ (Force due to kinetic friction)

We can plug in given values to solve for the frictional force:

ma = Fa - Fκ

(4)(1) = 8 - Fκ

4 = 8 - Fk

Fκ= 4N (negative since working opposite to acceleration)

Now, solve given the new force:

4a = 16 - 4

4a = 12

a = 3 m/s², Answer C.

You push the sofa across the floor. Which force is NOT present on the sofa?
a)gravity
b)normal
c)tension
d)applied

Answers

Answer:

c) tension ........ ........

Answer:

gravity

Explanation:

because it cannot be move across if there is present gravity force

how many atoms are in the moon??

Answers

The number of atoms on the moon is 1.33× 10¹⁵ atom.

What is an atom?

The atom consists of matter that may be split without releasing electrical charges.

It's also the smallest unit of matter with chemical element features. As a result, the atom is the fundamental unit of science.

In the nucleus proton and the neutron is exists. The condition of the atom to be electrically neutral is that the number of the proton and electron should be the same.

The response is 1.33× 10¹⁵ atom. According to the Jefferson Lab of the US Department of Energy.

This answer is derived from an assessment of the number of atoms present in each of the Earth's constituent elements, such as silicon, iron, magnesium, sulfur, and silicon.

Hence the number of atoms on the moon is 1.33× 10¹⁵ atom.

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How does a balanced chemical equation demonstrate the Law of Conservation of Mass?

Answers

Answer:

It shows the same number of atoms of each element on both sides of the equation

A balanced equation demonstrates the conservation of mass by having the same number of each type of atom on both sides of the arrow.

Explanation:

Matter cannot be created or destroyed in chemical reactions. This is the law of conservation of mass. In every chemical reaction, the same mass of matter must end up in the products as started in the reactants. Balanced chemical equations show that mass is conserved in chemical reactions.

A balanced chemical equation shows that total number of atoms before reaction is equal to total number of atoms after the reaction. As, the total mass of any object lies on its atom, a balanced chemical equation demonstrate the Law of Conservation of Mass.

What is Dalton's atomic theory?

The Dalton's atomic theory is as follows:

Atoms are the incredibly minuscule building blocks of all stuff.A given element's atoms are all the same size, mass, and other characteristics. Distinct elements' atoms have different mass, size, and other characteristics.Atoms can never be divided, produced, or eliminated.Chemical compounds can be created by combining atoms of various elements in straightforward whole number ratios.Atoms can be joined together, split apart, or altered during chemical processes.

The total number of atoms before and after a reaction are equal, according to a chemical equation that is in balance. A balanced chemical equation illustrates the Law of Conservation of Mass since every object's atom holds the entirety of its mass.

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Angelica has sprained her ankle and needs to stay off it for a few weeks, which is really frustrating because she is on the track team. She is worried that a prolonged period of inactivity will hurt her training. After about 10 days, she thinks that she can start working out gradually if she takes painkillers right before her workout. What is the BEST response to Angelica?

OPTIONS:

A.
She could really injure herself with this plan since she will not feel pain.
B.
Trying it once or twice and seeing how she feels is probably the best way to go.
C.
It is a common technique and lots of athletes practice injured so she will be fine.
D.
The damage from working out is probably less than the issue exercise will create.

PLEASE NO LINKS

Answers

Answer:

I think the answer is c

Explanation:

Because It is a common technique and lots of athletes practice injured so she will be fine.

By working on the given plan, Angelica can injure herself since she will not feel pain. The correct option is A.

What is ankle sprain?

A sprain takes place when your ankle is compelled to move out of its regular place, causing one or more of the ligaments in your ankle to stretch, partially tear, or completely tear.

A sprained ankle can be caused by a fall that causes your ankle to twist. Landing on your foot awkwardly after jumping or pivoting.

You should avoid strenuous exercises, such as running, until the pain and swelling have subsided, but you should keep moving so that the muscles and ankle do not stiffen. Once your ankle is less painful, begin some gentle exercises.

As she is having ankle sprain, and she is planning to take pain killers and start to work out, this can cause her even more problem as she will not feel any pain.

Thus, the correct option is A.

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P1= 100 kPa
V1= 5 L
T1= 300 degrees Kelvin
P2=100 kPa
V2= ? L
T2= 350 degrees Kelvin

Answers

Explanation:

using Charles law; since the pressure is constant

V1/T1 = V2/T2

5/300 = V2/350

cross multiply

V2 X 300 = 5 X 350

V2 = 1750/300

V2 = 5.833L

a car in tally at rest pics up and velocity of 72 km/h ^−1over a distance of 25m the acceleration of car is​

Answers

Answer:

16 m/s^2

You find out the time first which is 1.25s

Given w= 4+,- 0.02 A=2.0+,-0.2 and 3.0+,-0.6 what is the value of w\ A y square

Answers

Explanation:

w = (4.52 ± 0.02) cm, x = ( 2.0 ± 0.2) cm, y = (3.0 ± 0.6) cm. Find z = x + y - w and its uncertainty.

z = x + y - w = 2.0 + 3.0 - 4.5 = 0.5 cm

Dz = Dx + Dy + Dw = 0.2 + 0.6 + 0.02 = 0.82 rounding to 0.8 cm

So z = (0.5 ± 0.8) cm

Solution with standard deviations, Eq. 1b, Dz = 0.633 cm

z = (0.5 ± 0.6) cm

Notice that we round the uncertainty to one significant figure and round the answer to match.

When you describe a liquid as thick, are you saying that it has a high or a low viscosity?

Answers

It is commonly perceived as "thickness", or resistance to pouring. Viscosity describes a fluid's internal resistance to flow and may be thought of as a measure of fluid friction. Thus, water is "thin", having a low viscosity, while vegetable oil is "thick" having a high viscosity.

The liquid with greater thickness will be more viscous since it flow speed is lower. Therefore, the more thick liquids is more viscous and flow slowly.

What is viscosity ?

Viscosity of a liquid is the resistance to its flow. Viscosity depends on the density and thickness of the liquid. The more thicker the liquid the more viscous it will be.

Less thick liquids will flow fastly. For example water is a less viscous liquid as we see it flow so quickly. Whereas, honey, oil, etc are more viscous and the mobility of their liquid particles are resisted by viscosity.

The more viscous liquids generally has higher specific heat capacity as in the case of water and oil. The particle - particle attractive force is higher in highly viscous liquids.

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A golf ball is launched horizontally at a speed of 11 meters per second and a high of 6.4 m above the ground. How long will it take for the golf ball to reach the ground?

Answers

The answer is A.

t = ( 2h / g )^1/2 = ( 2 x 6.4 / 9.8 )^1/2 = 1.14s

What does it mean when an
electromagnetic wave has low energy?

A. it has a long wavelength

B. It has a short wavelength

C.it has a short amplitude

D. It has a high frequency

Answers

Answer:

A

Explanation:

Low energy photons (such as radio photons) behave more like waves, while higher energy photons (such as X-rays) behave more like particles.

Please give brainliest

Answer:

B. It has a short amplitude.

:)

how would a rock respond to stresses applied at depth?

Answers

The rock will compress as the stress applied increases with depth and it will break when it cannot withstand the stress.

The pressure or stress on the rock is defined as force per unit area of the rock which equally increases with depth. This can be expressed as follows;

[tex]P= \frac{F}{A}\\\\P = \rho gh[/tex]

where;

P is the pressure applied to the blockA is the area of the rock h is the depth in which the rock is subjected to g is acceleration due to gravity

Thus, we can conclude that the stress on the rock will increase with increase in depth. The rock will compress as the stress applied increases with depth and it will break when it cannot withstand the stress.

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white light such as that from the sun is actually only ultraviolet light.?

Answers

Answer:

no

Explanation:

White light, which is the visible light, from the sun contains all the rainbow colors; however, ultraviolet is a radiation emitted from the sun and it is nonvisible to humans.

No white light and ultraviolet light are the two types of radiation coming from the sun.

What are solar radiations?

The light coming from the sun contains different types of radiation that travel at different wavelengths this radiation is called solar radiation.

Types of solar radiation are visible light, ultraviolet light, infrared, radio waves, X-rays, and gamma rays.

Due to this visible light, we can see on earth because it has the frequency that our eyes can see.

visible light contains seven colors that are at different wavelengths. So when the diffraction of visible light takes place we can see these seven colors.

Thus white light and ultraviolet light are the two types of radiation coming from the sun.

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Guide Questions:


1. What is the speed of sound at the lowest temperature? __________________

2. What is the speed of sound at the highest temperature? _________________

3. At which temperature the speed of sound slowest? _____________________

4. At which temperature the speed of sound fastest? _____________________

5. Does temperature affect the speed of sound? Explain ___________________​

Answers

Answer:

1- 330.4m/s

2-358.0m/s

3- -1c

4- 45c

5- when temperature increase speed of sound will increase

1. The speed of sound at the lowest temperature in the image is 330.4 m/s.

2. The speed of sound at the highest temperature in the image is 358.0 m/s.

3. The temperature at which the speed of sound is slowest is -1°C.

4. The temperature at which the speed of sound is fastest is 45°C.

5. Yes, temperature affects the speed of sound.

The image shows the relationship between temperature and speed of sound in air. The x-axis of the graph shows the temperature in degrees Celsius, and the y-axis shows the speed of sound in meters per second. The line on the graph shows that the speed of sound increases with temperature. For every 1 degree Celsius increase in temperature, the speed of sound increases by about 0.6 m/s.

The speed of sound in air is also affected by other factors, such as humidity and air pressure. However, temperature is the most important factor affecting the speed of sound.

The speed of sound at the lowest temperature in the image is 330.4 m/s, which is at -1°C.

The speed of sound at the highest temperature in the image is 358.0 m/s, which is at 45°C.

The temperature at which the speed of sound is slowest is -1°C.

The temperature at which the speed of sound is fastest is 45°C.

Yes, temperature affects the speed of sound. The speed of sound increases with temperature. This is because the molecules of a medium vibrate faster at higher temperatures, and this allows sound waves to travel more quickly.

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Pendulum mass is 4 kg. Use your equations for gravitational potential energy and kinetic energy to determine these values based on the data given below. Total energy is the sum of gravitational potential energy and kinetic energy. In this problem, round gravity to: g = 10 m/s2.

Answers

its should be 2.0 and 4.5 on it

A 63 kg boy and sled are pulled along level ground with a force of 577 N. The boy and sled
are moving at a constant velocity of 2.4 m/s. What is the size of the frictional force?

Answers

Answer:

The size of the frictional force is 577 N.

Explanation:

What is frictional force?

Frictional forces are exerted every time you have two surfaces sliding across one another. Friction depends on:

how rougher are the surfaces on contact;how harder you push one surface to the other.

There are two types of friction:

static friction [tex]f_s[/tex];dynamic (sliding) friction [tex]f_d[/tex].

Now let's attack the problem:

First, you have to write the data down:

[tex]\bullet \quad m= 63\,kg\\\\\bullet \quad F= 577\,N\\\\\bullet \quad v= 2.4\,m/s[/tex]

If the boy and the sled moves on constant velocity, Newton's First Law Of Motion states that the net force acting on them must be zero:

[tex]F_{net}=0[/tex]

Applying Newton's Second Law Of Motion, we get:

[tex]F-f_d=0[/tex]

which means that:

[tex]F=f_d[/tex]

In other words, the dynamic frictional force equals the force that moves the boy and sled. So we may write:

[tex]\boxed{f_d=577\,N}[/tex]

Conclusion: the size of the (dynamic) frictional force is 577 N.

Happy studying!

Brainly Team

Describe the relationship between the state of matter of water (gas, liquid, solid) and the motion of the water molecules.

Answers

Answer:

ok

Explanation:

solid- molecules are close together and vibrating

liquid - molecules are loser, faster moving and take the shape of its container

gas- fast moving molecules and take whatever shape they want (like a room or the air outside)

Explanation:

Solids: The inter-molecular attraction force is the highest and the inter-molecular distance is the least. Solids have definite shape and volume.

Liquids: The inter-molecular attraction force is less than that of solids and the inter-molecular distance is more than solids. Liquids have definite volume but no definite shape.

Gases: The inter-molecular attraction force is the least and the inter-molecular distance is the highest. Gases have no definite shape or volume.

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