In positron-emission tomography (PET) used in medical research and diagnosis, compounds containing unstable nuclei that emit positrons are introduced into the brain, destined for a site of interest in the brain. When a positron is emitted, it goes only a short distance before coming nearly to rest. It forms a bound state with an electron, called "positronium", which is rather similar to a hydrogen atom. The binding energy of positronium is very small compared to the rest energy of an electron. After a short time the positron and electron annihilate. In the annihilation, the positron and the electron disappear, and all of their rest energy goes into two photons (particles of light) which have zero mass; all their energy is kinetic energy. These high energy photons, called "gamma rays", are emitted at nearly 180° to each other. What energy of gamma ray (in MeV, million electron volts) should each of the detectors be made sensitive to? (The mass of an electron or positron is 9 × 10-31 kg. 1 eV = 1.6 × 10-19 joules.

Answers

Answer 1

Answer:

Energy of gamma ray = 506250 eV

Explanation:

We are told that the mass of an electron or positron is 9 × 10-31 kg.

This means that their energies will be the same.

Thus; E_e = E_p

Now, since electron and positron annihilate to form gamma(γ) particle, then using work energy principle, we have;

E_γ + E_γ = E_e + E_p

Thus;

2E_γ = E_e + E_p

Since E_e = E_p, we now have;

2E_γ = 2E_e

Thus;

E_γ = E_e

Since all the energy of the electron is converted, then from Einstein's relativity theory, this implies that;

E_e = mc²

c is speed of light = 3 × 10^(8) m/s

And m is given as 9 × 10^(-31) kg

Thus;

E_e = 9 × 10^(-31) × (3 × 10^(8))^(2)

E_e = 810 × 10^(-16) J

Since E_γ = E_e

Thus;

E_γ = 810 × 10^(-16) J

We are given that; 1.6 × 10^(-19) J = 1eV

Thus; 810 × 10^(-16) J gives;

(810 × 10^(-16) × 1)/(1.6 × 10^(-19)) = 506250 eV


Related Questions

A pigeon takes off from where it was initially on the ground, near where home base is located at Regions Field (close to 1st Ave. South and 14th street in Birmingham), and the bird flies at what you can consider a constant speed of 18 m/s along a direct straight line to Birmingham International Airport, where he lands on the roof of one of the main terminals there. 5.E. How many seconds does it take the bird to make this trip

Answers

Answer:

1.84 seconds

Explanation:

Given

initial velocity u = 0m/s

final velocity v = 18m/s

To get the time it takes the bird to make this trip, we will use the equation of motion

v = u+gt

g is the acceleration due to gravity = 9.81m/s²

t is the time

Substitute into the formula:

[tex]18 = 0+(9.81)t\\18 = 9.81t\\9.81t = 18\\t = \frac{18}{9.81}\\ t = 1.84secs[/tex]

Hence it took the bird 1.84seconds to make this trip

A car travels 85 km in the first half hour of a trip. The car continues to travel for 2 more hours and travels 200 km. What was the average speed of the car for the trip?

Answers

Answer:

50

Explanation:

A 1-kilogram object is thrown horizontally and a 2-kilogram object is dropped vertically at
the same instant and from the same point above the ground. Which of the following will
be the same for both objects at any given instant?

Answers

Their vertical position will be the same for both at any instant. They will both hit the ground at the same time.

Acceleration is the change in the velocity of the object with time. Acceleration is the same for both objects so both objects will reach the ground at the same time.

How do you find out the common value for both objects?

Given that both the object dropped at the same time. So the gravitational acceleration of both the objects will be the same which is nearly 10 m/s.

The force at object 1 is given below.

[tex]F_1 = m_1\times g = m_1\times a_1[/tex]

Where m1 is the mass of object 1 and a1 is the acceleration of object 1.

[tex]F _1 = 1\times 10 = 10 \;\rm N[/tex]

The acceleration of object 1 is calculated as below.

[tex]a_1 = \dfrac{F_1}{m_1}[/tex]

[tex]a_1=\dfrac{10}{1} = 10 \;\rm m/s^2[/tex]

The force at object 2 is given below.

[tex]F_2 = m_2\times g = m_2\times a_2[/tex]

Where m2 is the mass of object 2 and a2 is the acceleration of object 2.

[tex]F_2 = 2\times 10 =20 \;\rm N[/tex]

The acceleration of object 2 is calculated as below.

[tex]a_2 = \dfrac{F_2}{m_2}[/tex]

[tex]a_2=\dfrac{20}{2} = 10 \;\rm m/s^2[/tex]

Hence we can conclude that the acceleration of both the objects is the same at every point so they will reach the ground at the same time.

To know more about the acceleration, follow the link given below.

https://brainly.com/question/12134554.

What are some things that can impact your mental health?

Answers

What people say to you

A car traveling at 30 m/s is brought to rest at a constant rate in 20 s by applying the brake. a) What is its acceleration? b) How far did it travel after the brake was applied?

Answers

acceleration = -30/20 = -1.5 m.s^2
V^2 = U ^2 + 2 a s
0 = 900 - 2 x 1.5 x s
3 s = 900
s = 300 m


A car is traveling at a speed of 45 km/h into town. It takes the car 2 hours to get there. How far has the car traveled?

Answers

Answer:

90 km

Explanation:

45 km per hr

2 hrs

45 x 2 = 90

90 km/2 hrs

Hope this helps!

The car traveled 90 km
If the car is traveling 45 km per hour you just need to double it by multiplying it by 2 to get 2 hours

A planet similar to the Earth has a radius 7.4 × 106 m and has an acceleration of gravity of 10 m/s 2 on the planet’s surface. The planet rotates about its axis with a period of 25 h. Imagine that the rotational speed can be increased. If an object at the equator is to have zero apparent weight, what is the new period? Answer in units of h.

Part 2:
By what factor would the speed of the object be increased when the planet is rotating at the higher speed?

Answers

Answer:

1.5 hr

16.7

Explanation:

Zero apparent weight means there's no normal force.

Sum the forces in the centripetal direction.

∑F = ma

mg = mv²/r

v = √(gr)

v = √(7.4×10⁶ m × 10 m/s²)

v = 8602 m/s

The circumference of the equator is:

C = 2πr

C = 2π (7.4×10⁶ m)

C = 4.65×10⁷ m

So the period is:

T = C / v

T = (4.65×10⁷ m) / (8602 m/s)

T = 5405 s

T = 1.5 hr

The initial speed is:

v = C / T

v = (4.65×10⁷ m) / (25 h × 3600 s/h)

v = 517 m/s

The speed increases by a factor of:

8602 m/s / 517 m/s

16.7

The new period of the planet at the given radius is 1.5 h.

The speed of the planet increased by a factor of 16.7.

The given parameters;

radius of the Earth, R = 7.4 x 10⁶ macceleration due gravity, g = 10 m/s²period, T = 25 h

The speed of the planet at the given radius is calculated as follows;

[tex]mg = \frac{mv^2}{r} \\\\gr = v^2\\\\v= \sqrt{rg} \\\\v = \sqrt{7.4 \times 10^6 \times 10} \\\\v = 8602.3 \ m/s[/tex]

The new period of the planet is calculated as follows;

[tex]T = \frac{2\pi R}{v} \\\\T = \frac{2 \pi \times 7.4 \times 10^6}{8602.3} \\\\T =5,405.72 s \\\\T = \frac{5405.72}{3600} = 1.5 \ hr[/tex]

The initial speed of the planet is calculated as follows;

[tex]v_i = \frac{2\pi R}{T} \\\\v_i = \frac{2\pi \times 7.4\times 10^6}{25 \times 3600} \\\\v_i =516.68 \ m/s[/tex]

The increase in the speed of the planet is calculated as;

[tex]= \frac{v}{v_i} \\\\= \frac{8602.3}{516.68} \\\\= 16.7[/tex]

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what’s the answer?? middle question

Answers

The new volume = 3 x 52.6 that’s because as the pressure decreases by 1/3 the volume increases x3

A man starts walking at a steady speed of 1 m/s and 6s later his son sets off from the same point in pursuit of him, starting at rest and accelerating at 2/3 m/s/s. How far do they go before they are together?

Answers

Answer:

The father will walk 6 more meters and the son will walk 12 meters

Explanation:

Uniform Speed and Acceleration

This is a problem where two objects have different types of motion. The father walks at a constant speed and later, his son starts a constant acceleration motion in pursuit of him.

Let's start with the father, whose speed is v=1 m/s during t=6 seconds. He travels a distance:

[tex]x=vt=1*6=6\ m[/tex]

Now the son, starting from rest (vo=0) accelerates at a=2/3 m/s^2. His speed will increase and eventually, he will catch up with his father. Let's suppose it happens at a time t1.

The distance traveled by the son is given by:

[tex]\displaystyle xs=v_o.t_1+\frac{a.t_1^2}{2}[/tex]

Since vo=0:

[tex]\displaystyle xs=\frac{a.t_1^2}{2}[/tex]

The father will continue with constant speed and travels a distance of:

[tex]xf=v.t_1[/tex]

For them to catch up, the distance of the son must be 6 m more than the distance of the father, because of the leading distance he has already taken. Thus:

[tex]xs=xf+6[/tex]

Substituting the equations of each man:

[tex]\displaystyle \frac{a.t_1^2}{2}=v.t_1+6[/tex]

We know a=2/3, v=1:

[tex]\displaystyle \frac{2}{3}\cdot\frac{t_1^2}{2}=t_1+6[/tex]

Simplifying:

[tex]\displaystyle \frac{t_1^2}{3}=t_1+6[/tex]

Multiply by 3:

[tex]t_1^2=3t_1+18[/tex]

Rearranging:

[tex]t_1^2-3t_1-18=0[/tex]

Factoring:

[tex](t_1-6)(t_1+3)=0[/tex]

Solving:

[tex]t_1=6 , t_1=-3[/tex]

Since time cannot be negative, the only valid solution is

[tex]t_1=6\ s[/tex]

The distance traveled by the son in 6 seconds is:

[tex]\displaystyle xs=\frac{2/3\cdot 6^2}{2}[/tex]

[tex]xs=12\ m[/tex]

Note the father will travel

[tex]xf=1*6=6\ m[/tex]

This 6 m plus the 6 m he was ahead of the son, make them meet while walking at 6 seconds.

Answer: The father will walk 6 more meters and the son will walk 12 meters

Work occurs when (2 points) an applied force results in movement of an object in the same direction as the applied force an object is subjected to balanced forces resulting in movement of the object the energy present is the result of the force acting on the object the movement of the object was caused by a force and is in the opposite direction of the force

Answers

Answer:

.

Explanation:

Can air be forced into a smaller space? Explain with an example.
I will give out brainliest to person who has best answer☺️

Answers

Answer:

Yes. Yes, you can.

Explanation:

Combinations of increased pressure and decreased temperature force gases into containers that we use every day. You might have compressed air in a spray bottle or feel the carbon dioxide rush out of a can of soda. Those are both examples of gas forced into a smaller space at a greater pressure.

Hope this helps :)

If you had a 30 pound barbell at home and you wanted to compare your muscular endurance to your younger brother's which method would be the best to use.

Answers

Answer:A

Explanation:

Absolute method

Answer:

absolute method

Explanation:

trust

I really need help on this.

Answers

Earth's rotation is crucial to understanding the Coriolis effect. The Equator is where Earth rotates more quickly than the poles. There at Equator, Earth is larger.

Equatorial areas therefore move at a speed of around 1,600 km/h (1,000 mph) in a 24-hour period to complete a revolution. Earth rotates slowly towards to the poles, at 0.00008 km/h (0.00005 mi/h).

Low-pressure systems called cyclones draw air towards their "eye" or central region. Fluids representing high-pressure systems in the Northern Hemisphere pass low-pressure regions to the right.

Air masses are deflected when they're drawn inside cyclones from across all sides, giving the appearance that a hurricane is rotating clockwise. Trade winds refer to these air masses' recurrent circulation patterns.

To know more about speed click here

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The diameter of a hydrogen atom is 0.000000000106 m. How can this
number best be expressed in scientific notation?
O A. 10.6 x 10-9 m
O B. 1.06 x 10-9 m
O C. 1.06 x 10-10 m
O D. 1.06 -1010 m
( please help me! )

Answers

Answer:

The diameter of a hydrogen atom based on scientific notation is 1.06 x 10^-10 m

The diameter of a hydrogen atom is 0.000000000106 m. This is number can best be expressed in scientific notation as 1.06 x 10⁻¹⁰ m. Hence, option (C) is correct.

What is scientific notation?

Scientific notation is a means to express values that are either too big or too little to be conveniently stated in decimal form (typically would result in a long string of digits). It is also known as standard form in the UK and scientific form, standard index form, and standard form.

Scientists, mathematicians, and engineers frequently utilize this base ten notation because it can make some mathematical operations simpler. It is typically referred to as "SCI" display mode on scientific calculators.

As there has 9 zeros after the decimal, this number can best be expressed in scientific notation as 1.06 x 10⁻¹⁰ m.

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Which of the following represents an example of thermal energy?
O a
Saxophone
Ob
Oven
с
Powerlines
Od
Windmill

Answers

Answer:

The answer of this question is windmill

A tennis ball is released from a height of 2.0 m above the floor, and then bounces three times. With each bounce, dissipative forces cause it to lose 16.0% of its mechanical energy. How high does it reach after the third bounce?

140 cm

120 cm

120 mm

12 cm

Answers

Answer:

12 cm

Explanation:

From what I got with my answer (8.192 cm) I went ahead and rounded it to the closest answer which is 12 cm. Hopefully im correct but if not, I apologize in advance.

I would definitely say D: 12cm
Anything higher than i’d say 70 cm is false and it’s way to much. Thank you!!!

which one is the biggest unit of plane angle
radian degree or revolution

Answers

Answer:

i think radian degree thank you

Explanation:

cuz right the degree angle i responsible more

Answer:

Its radian degree

Explanation:

Because the length of an arc of a unit circle is equal to measurement in radians of angle.

So it is the biggest unit of plane angle

PLEASE HELP
Question 4 of 10
Which statement is true of a piece of ice at 0°C that is put into a freezer at
-18°C?
A. The ice cube will remain unchanged.
B. The ice cube will gain mass from the surroundings.
C. The ice cube will lose thermal energy to the surroundings.
D. The ice cube will gain thermal energy from the surroundings.

Answers

The ice cube will lose thermal energy to the surroundings. The given statement is true of a piece of ice at 0°C that is put into a freezer at -18°C. Thus, the correct option is C.

What is thermal energy?

The term thermal energy is used loosely in various different contexts in physics and engineering mainly. Thermal energy can refer to several different well-defined physical concepts. These concepts include the internal energy or the enthalpy of a body of matter and the radiation energy, the heat energy, which is defined as a type of energy transfer and it is the characteristic energy of a degree of freedom.

If a piece of ice at 0°C that is put into a freezer at -18°C then it can be said that the ice cube will lose thermal energy to the surroundings.

Therefore, the correct option is C.

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what happends when you slowly pull out the paper while theirs a coin on top​

Answers

The coin would probably slowly slide down whichever end it is closer to, weigh down the end of the paper, and fall off. It kinda depends on how you hold the paper though, because if it is directly in middle, and you hold it on both ends, it will stay on the paper.
The correct answer is “ the coin will stay on the same place on the paper and will move along with the paper “

A chemical symbol is to an element as a chemical formula is to a(n)

Answers

A subscript is the answer

ILL GIVE BRAINLIEST AND 5 POINT STAR RATING!!!! Which cultural region of the United States has the most Native American influence today? 1.South 2.Northeast 3.Midwest 4.West

Answers

Answer:

The answer is 4, the west.

Answer:

The west

Explanation:

hopes this helps you and your questions

3. A substance has a density of 19.3 g/ml. What is the volume of 20.2 g of the
substance? Hint: density can be used as a conversions factor

Answers

Answer:

The answer is 1.05 mL

Explanation:

The volume of a substance when given the density and mass can be found by using the formula

[tex]volume = \frac{mass}{density} \\ [/tex]

From the question we have

[tex]volume = \frac{20.2}{19.3} \\ = 1.04663212...[/tex]

We have the final answer as

1.05 mL

Hope this helps you

Explain why the interconnection is not valid. Explain why the interconnection is not valid. A valid interconnection would require the 3 AA and 4 AA sources to supply different currents in the same direction, which they do not. A valid interconnection would require the 3 AA and 4 AA sources to supply different currents in opposite directions, which they do not. A valid interconnection would require the 3 AA and 4 AA sources to supply the same current in opposite directions, which they do not. A valid interconnection would require the 3 AA and 4 AA sources to supply the same current in the same direction, which they do not.

Answers

Complete Question

The diagram for this question is shown on the first uploaded image

Explain why the interconnection is not valid.

i A valid interconnection would require the 3 A and 4 A sources to supply different currents in the same direction, which they do not.

ii  A valid interconnection would require the 3 A and 4 A sources to supply different currents in opposite directions, which they do not.

iii  A valid interconnection would require the 3 A and 4 A sources to supply the same current in opposite directions, which they do not.

iv A valid interconnection would require the 3 A and 4 A sources to supply the same current in the same direction, which they do not

Answer:

The correct option is  iv

Explanation:

Looking at the diagram we see that the current source are connected in series, generally the current flowing through two source that are connected in series is suppose to be the same but in this case it is not so

i.e [tex]4A  \ne 3 A[/tex] hence Kirchhoff's law is broken or not followed in this circuit which means the interconnection is not valid  

also another reason why the interconnection is not valid is because the current are flowing in the different directions  

An airplane flying at 119 m/s is accelerated uniformly at the rate of 0.5 m/s2 for 10
seconds. What is its final speed?

Answers

Answer:

124m/s

Explanation:

v=u+at

v=119+(0.5×10)

v=119+5

v=124m/s

How do waves transfer energy? Be detailed.

Answers

Answer:

Electromagnetic waves transfer energy through vibrations of electric and in magnetic fields. For sound waves the energy is transferred through the vibration of air particles or particles of a solid. Waves also carry energy, the amount of energy they carry depends on their frequency and their amplitude. The more energy and the higher frequency amplitude, the more energy waves are ^‿^

An astronaut weighing 588 N on earth notices that he weighs only 98 N on moon. His mass on moon is blank kg

Answers

Answer:

60 kg

Explanation:

An astronaut weighs 588 N on the earth

He also weighs 98 N on the moon

Therefore the the mass of the astronaut on the moon can be calculated as follows

= 588/98

= 6 × 10

= 60 kg

Hence the mass of the astronaut on the moon is 60 kg

The mass of the astronaut on the moon will be equal to 60 kg whereas the gravitational acceleration on the moon is 1.63 [tex]\rm m/s^2[/tex].

Given information:

An astronaut weighing 588 N on the earth notices that he weighs only 98 N on the moon.

The mass of any object in the whole universe doesn't change but the gravitational force or weight can change. This is because the gravitational acceleration can change.

The mass of the object in the earth or anywhere will be,

[tex]w=mg\\588=m\times 9.8\\m=60\rm \; kg[/tex]

So, the astronaut has 60 kg mass which is constant.

The gravitational acceleration on the moon will be,

[tex]98=60a\\a=1.63\rm\; m/s^2[/tex]

Therefore, the mass of the astronaut on the moon will be equal to 60 kg whereas the gravitational acceleration on the moon is 1.63 [tex]\rm m/s^2[/tex].

For more details, refer to the link:

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Wanda is afraid of gaining weight and putting herself at high risk for disease. she works out on a regular basis and eats right most of time. recently, Wanda some testing done. her BMI with some 17.2 and her waist circumference is 30 inches. what statement best describes next move for Wanda so she will be at the least risk for disease?​

Answers

Answer:

C. Wanda's waist circumference indicates that she is not at risk, but her BMI indicates that she underweight. She should develop a plan to move her BMI into the normal range.

Explanation:

edge 2020 Brainliest would be appreciated

Answer:

Wanda's waist circumference indicates that she is not at risk, but her BMI indicates that she underweight. She should develop a plan to move her BMI into the normal range.

Explanation:

I just did the Cumulative Exam Review

A freight train car has a mass of 2,000 kilograms and an acceleration of 1.8 m/s/s. ​What is the average force behind that train car?

Answers

Answer:

F = 3600 [N]

Explanation:

To solve this problem we must use Newton's second law, which tells us that the sum of force must be equal to the product of mass by acceleration.

ΣF = m*a

where:

F = force [N]

m = mass = 2000 [kg]

a = acceleration = 1.8 [m/s^2]

Now replacing:

F = 2000*1.8

F = 3600 [N]

A motorcycle is stopped at a stop light. When the light turns green it
accelerates at 4.2 m/s^2. How far does it travel during 3 s? *

Answers

Answer: 18.9 m

Explanation:

i did the kinematic equation & found the answer.

A body starts with a velocity of 20 m/s, accelerates uniformly for a time t, moves with constant velocity for the same time, and finally decelerates to rest, again taking a time t. Given that the final deceleration is three times the original acceleration, and the total distance travelled is 140 m, find t.

Answers

Answer:

t=0.14s

Explanation:

t=[tex] \frac{s}{v} [/tex]t=[tex] \frac{20}{140} [/tex]Where s= speedV=distance And t=time
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