The number of 22Na atoms in the initial sample N = 3.56 x 10¹² atoms. The activity of the sample is 1/4 of the initial activity: A = 7.5 x 10³ Bq.
The decay of radioactive isotopes follows an exponential decay law, which means that the amount of the radioactive substance remaining after a certain time can be expressed as a fraction of its initial amount. This fraction is determined by the isotope's half-life, which is the time it takes for half of the initial amount to decay.
In the case of 22Na, the half-life is 2.6 years. This means that after 2.6 years, half of the original 22Na atoms would have decayed, and only half would remain. After another 2.6 years, half of the remaining atoms would decay again, leaving only one-quarter (1/2 x 1/2 = 1/4) of the original number of atoms.
So, if the initial sample contained N atoms of 22Na, after two half-lives, the remaining number of atoms would be N/4. This exponential decay of radioactive isotopes is the basis of many applications in science and technology, such as radiocarbon dating and nuclear power generation.
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14. If 100 grams of sodium nitrate are dissolved in 100 grams of water
at 60 degrees C, is the solution formed saturated, unsaturated, or
supersaturated?
Answer:
Unsaturated
Explanation:
the solubility of sodium nitrate is at 60 C is 124g/ml therefore, putting 100 grams will not saturate fully.
A 2 kg ball is thrown down with 50J of energy from a height of 10m, what is its velocity before it strikes the ground (neglect air resistance).
Answer:
V=14
Explanation:
PE=KE
mgh=1/2mv^2
(2)(9.8)(10)=1/2(2)v^2
(radical) 196=(radical) v
V=14
what are the unique characteristics of romantic music which are not present in Original Pilipino Music (OPM)
Answer:
ITU Sangat bermanfaaat
how you would orient the magnets and what you would do with the magnets to achieve maximum repulsion
The orientation of the magnets that gives the strongest repulsion because these poles and facing each other that is then leaves highest flux density of the poles for a force of repulsion to be very high
Motion and acceleration may only be used to refer to physical objects moving or changing speed/direction
Answer:
True
Explanation:
It is TRUE that Motion and acceleration may only be used to refer to physical objects moving or changing speed/direction.
This is because if an object is not moving or changing speed/direction to a determined point of reference, the object is considered to be at rest or motionless, thereby, with no absolute point of reference, absolute motion or acceleration cannot be distinguished.
6. Suppose the resistance of your body between your right and left hands is 500,000 N. What
would be the current flowing through your body if you touched the plus and minus terminals of
a 120 V battery? The threshold of sensation for electric current through your body is about
300 PA. Would you feel the current?
HELP PLS
The electrostatic force between two charged metal spheres is 2N. If the charge on each sphere is doubled, what is the new force between the spheres?
Question 2 options:
A. 2N
B. 4N
C. 1N
D. 8
Answer:
8 N
Explanation:
The force between two charges is given by :
[tex]F=\dfrac{kq_1q_2}{d^2}[/tex]
Where
k is electrostatic constant
d is the distance between two charges
It means,
[tex]F\propto \dfrac{1}{d^2}[/tex]
When the distance is d, the force is 2 N. If the charge on each sphere is doubled, q₁' = q₂' = 2q₁ = 2q₂. New force will becomes:
[tex]F'=\dfrac{kq_1'q_2'}{d^2}\\\\F'=\dfrac{k2q_1\times 2q_2}{d^2}\\\\F'=4\times \dfrac{kq_1q_2}{d^2}\\\\F'=4\times 2\\\\F'=8\ N[/tex]
So, the new force becomes 8N. Hence, the correct option is (d).
If a girl walks 6km due west changes directions and walk another 5km due north. Find her displacement in both magnitude and direction
Answer:
the girl's displacement in both magnitude and direction is 7.81 m at 50.2⁰ North west.
Explanation:
Given;
6km due west, and
5km due north
The magnitude of her displacement is calculated by forming a right angled triangle. The hypotenuse side of the triangle is the girl's displacement.
d² = 5² + 6²
d² = 25 + 36
d² = 61
d = √61
d = 7.81 m
The direction of the girl is calculated as;
[tex]tan \ \theta = \frac{6}{5} \\\\tan \ \theta = 1.2\\\\\theta = tan^{-1} (1.2)\\\\\theta = 50.2^0[/tex]
Therefore, the girl's displacement in both magnitude and direction is 7.81 m at 50.2⁰ North west.
The dog has ran 100 meters in 20 seconds and then 300 meters in 25 seconds what was the average speed of the dog over the entire time it was running
Explanation:
the speed of the dog was 400
write any four importance of pressure
Answer:
Here is your ans
Explanation:
hope it helps you tq
state and explain the joules law
Answer:
Joule’s law of heating states that when a current ‘i ' passes through a conductor of resistance ‘r’ for time ‘t’ then the heat developed in the conductor is equal to the product of the square of the current, the resistance and time.
H = i 2 rt
The reason behind the heat produced is the collision of the free electrons with the lattice ions or atoms while accelerating in presence of the external electric field.
we know that
volt= work done/ total charge or v = w/q
from this we get w= vq
we know that current i = q / t
so q = it
putting this in prev equation
we get w = vit
from ohms law v = ir
putting it in prev eq we get
w = irit = i2rt joule as work is stored as heat soH = I2RT Joules
if a current carrying conductor having resistance (r) gets heated by to passing of current (i) for time (t) and the heat thereby produced be H
joules law states that
H propotional to i^ 2 when r and t are constant
H propotional to r when I and t are constant
H propotional to t when r and I constant
1:What kind of energy does your body use to keep you warm.
2: What are two examples of something that stores chemical energy
3: All forms of energy can be transferred into what?
4: When energy changes from one type to another, this is called what?
5: Friction created by a car tire rubbing on a road creates what energy transportation? {blank} energy into {blank energy}
6: What type of energy transformation occurs when oil is used to heat a home? {blank} energy into {blank} energy? ( this is due today and it would really help me out if you could help me)
Answer:
1. thermal energy
2. Batteries and coal
4. energy conversion
PLEASE HELP ME!!!! i will give brainliest to whoever gets it right
Answer:
I believe the answer is B.)
The ability of a halogen to react with a metals to form a salt is an example of a ________________ property.
what's 4 x 5
i need help with this question please
Answer:
4 × 5 = 5 + 5 + 5 + 5 = 20
Explanation:
Pick one factor and add it.
An 6 kg object accelerating from 17 m/s to 10 m/s. What is the change in momentum of the object?
Answer:
- 42
Explanation:
m = 6kg
vi = 17 m/s
vf = 10 m/s
delta mv = ?
Formula
delta mv = m*(vf) - m(vi)
delta mv = 6(10 - 17)
delta mv = 6(-7)
delta mv = - 42 kg m/s
On planet Q, g = 2.24 m/s2. If the mass of planet Q is 8.96
1021 kg, what is the radius of planet Q?(G = 6.67 * 10-11 N
(m/kg))
a
8.95 x 1032 m
b 5.17 x 10 m
C 1.26 108 m
d 9.23 x 1024 m
e
4.72 x 106 m
Answer:
5.17 x 10^5
Explanation
The correct answer is (b) [tex]5.17*10^{5}m[/tex]
Let us consider an object of mass m on the planet Q.
On planet Q, let the acceleration due to gravity be g = 2.24 m/[tex]s^{2}[/tex]
Mass of the planet is M = [tex]8.96*10^{21} kg[/tex]
Let its radius be R
and the universal gravitational constant G = [tex]6.67*10^{-11} m/kg[/tex]
Gravitational Force acting on the object:
[tex]mg=\frac{GMm}{R^{2} }[/tex]
[tex]R=\sqrt{\frac{GM}{g} } \\R=\sqrt{\frac{6.67*10^{-11}*8.96*10^{21} }{2.24} }\\R=5.17*10^{5} m[/tex] is the radius of the planet Q.
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a dolphin that just manage to keep up with a speeding boat for a distance of 2km for a period of 3h in (answer in km/h)
Answer:
6km
Explanation:
3hours X 2km = 6 kilometres
Long Answer Type Questions
1 Can you differentiate between opaque, transparent and translucent objects
2 What is reflection of light?
3. What are the conditions for a shadow to be formed?
4. Prove through an experiment that light travels in straight lines.
5. What is pinhole camera? Explain its working with the help of a diagram
6. What are the main differences between a reflected image and shadows?
(1).....opaque -object that not allow light to pass through it
we can't look through opaque objects
ex..wall
translucent... objects that all some light to pass through it
we can partially see through it
ex...coloured glass window
transparent... objects that wholly allow light to pass through it
we can clearly see through it
ex...glass of specs
(2)..the bouncing back of light from a smooth polished surface is called reflection of light
(3)/.....there must be a solid ,opaque to block light
there must be a source of light
there must be a surface to have shadow on it..
(6)...reflected images r formed by light reflection from a smooth polished surface while shadows are formed by blockage of light by an solid,opaque object...
Explanation:
we should talk here thanks
If a storm is 7.5 kilometers away, how much time is expected between observations of lightning and thunder?
Answer:
≈ 22 seconds
Explanation:
7,5 km = 7500 m
Speed of light 300 000 000 m/s (for lightning)
Speed of sound 343 m/s (for thunder)
time = distance / speed
lightning time = 7500 m / 300 000 000 m/s = 0.000025 s
thunder time = 7500 m / 343 m/s ≈ 22 s
thunder time - lightning time = 22 s - 0.000025 s ≈ 22 s
The electromagnetic spectrum is divided into regions by Group of answer choices a.wavelengths and frequencies b.the way they are used c.speed d.colors
Answer:
Generally, by wavelengths and frequencies.
Colors only occur for a narrow portion of the spectrum.
The speed for these waves is c the speed of light regardless of wavelength.
The way they are used seems somewhat irrelevant.
The electromagnetic spectrum is divided into regions by wavelengths and frequencies. The spectrum is arranged in the order of increasing frequency.
What is electromagnetic spectrum ?The electromagnetic spectrum is the arrangement of waves in the order increasing frequency or decreasing wavelength. The order of the spectra starts from radio waves, microwaves, infrared, visible light, ultraviolet, x -rays and gamma rays.
The visible light that we can see is in between IR and UV rays. Hence, visible light has a frequency greater than IR rays but shorter than IR. Similarly visible light is longer than UV- rays but less frequency than UV rays.
Gamma rays are the most energetic and shorter waves in the electromagnetic spectrum with smaller wavelength and greater frequency. Hence, options a is correct.
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Why is the overall charge of the atom neutral or zero?
A. The zero charge on the neutrons in the nucleus create a neutral atom.
B. The number of protons is equal to the number of electrons
C. Equal numbers of neutrons, protons, and electrons work together to keep the charge of the atom neutral or zero.
D. Atoms are not electrical and therefore have no charge.
Answer:
B
Explanation:
this is because the neutrons do not have a charge, the things that have charge in an atom are electrons and protons.
and in the nucleus of an atom, there are protons and neutrons so you can see that A is not the answer
if you see the periodic table, you will know that the number of electrons and protons are equal, so the charges cancel each other out, hence the charge of an atom will be neutral
let me give you a tip which I got from my teacher, never write there is no charge in the atom, this suggests that there is no protons or electrons.
instead, write, the it is neutral
hope it helps if not please report it so that someone else gets to try it out
PLS HELP. PLEASE. What is the role of DNA in determining an organism’s traits?
Answer using these words: DNA, chromosome, gene, allele, dominant, recessive
Answer:
DNA contains the instructions needed for an organism to develop, survive and reproduce. To carry out these functions, DNA sequences must be converted into messages that can be used to produce proteins, which are the complex molecules that do most of the work in our bodies
manganese dioxide is used in the dry cell as
Answer:
Electrolytic manganese dioxide (EMD) is used in zinc-carbon batteries together with zinc chloride and ammonium chloride. EMD is commonly used in zinc manganese dioxide rechargeable alkaline (Zn RAM) cells also. For these applications, purity is extremely important.
Explanation:
hope this helps...
3. Gather data: Use the values above to fill in the first row of the table. Then run your own experiments to fill
in the last two rows.
f
d.
d,
h.
h,
ร”
S
d
de
2.0
h;
h.
2.0
s.
2.0
S
f
2.0
15
10
30
Answer:
urjshsus uevus e survey dydvd dydvdyd d dgdv gdyr yrgdvv yth yrhvthr
Explanation:
ydgdydvd yd dv ydvr dyve dysdvdyr gdvr
Electric field strength of a point charge is E. What is the electric potential at a point where electric field will be E/4?
Answer:
Explanation:
We shall find first the distance where electric field is E/4 .
Let the charge be Q and distance be d where electric field is E . From the coulomb's Law
E = k Q / d²
Let distance be d₁ where field is E/4
E/4 = kQ / d₁²
Dividing the two equation
4 = d₁² / d²
d₁ = 2d
We shall have to find Potential at d₁ which is equal to 2 d .
Potential at d₁
V = k Q / 2d
= kQ d / 2d²
= E d / 2 . where d is distance of the point where field is E .
Explain how is the voltage across a resistor measured?
Answer:
You take the basic formula of E = I x R, solve for R -> R = E / I. In other words, take the required voltage drop (in volts) and divide by the current (in amps) in the resistor and determine the resistance (R) in ohms.
Explanation: hope this helps
The unit of power of a lens is.
(a) Metre
(b) Dyne
(c) Dioptre
Answer:
c. dioptre that's the answer.
The change in frequency of a wave as its source moves in relation to an observer.
A)
Ultrasound
B)
Frequency
C)
Doppler Effect
D)
Echo
Answer: B) Frequency
Explanation:
1. Compare the speed that light waves travel in air to the speed that sound waves travel in the air. How many times faster do light waves travel in air in comparison to sound waves in air?
Water-1500 meters per second
steel-5000 meters per second
Air-335 meters per second
Answer:
895522 times faster.
Explanation:
From the question given above, the following data were obtained:
Speed of sound in air (v) = 335 m/s
Speed of light in air (c) = 3×10⁸ m/s
How many times faster =.?
To obtain how many times faster light travels in air than sound, do the following
c : v => 3×10⁸ : 335
c/v = 3×10⁸ / 335
c/v = 895522
Cross multiply
c = 895522 × v
From the illustrations made above, we can see that the speed of the light in air (c) is 895522 times the speed of sound in air.
Thus, light travels 895522 times faster than sound in air.