Answer:
20
Explanation:
Atomic number is same as the number of protons of an atom and atomic mass is equal to the sum of number of protons and number of neutrons of an atom.
Atomic number = 19
So, number of protons (p) = 19
Atomic mass = 39
So, sum of number of neutrons and number of protons (n + p) = 39
Number of neutons (n)
= (n + p) - p
= 39 - 19
= 20
Potassium’s atomic number is 19, and its atomic mass is approximately 39, then Potassium would have 20 neutrons present inside its nucleus, therefore the correct answer is option C.
What is the atomic number?The total number of protons present in an atom is known as the atomic number of that atom. The atomic number has no correlation either with the number of neutrons or the number of electrons present inside an atom.
While the atomic mass of an atom is the sum of the total number of protons and the number of neutrons present inside of any atom.
atomic number= total number of protons
atomic mass = total number of protons + total number of the neutrons
As given in the problem Potassium’s atomic number is 19, this means Potassium has 19 protons
Potassium has an atomic mass of about 39
39 = total number of protons + total number of the neutrons
39 = 19 + total number of the neutrons
total number of the neutrons = 39-19
=20
Since potassium has an atomic mass of about 39 and an atomic number of 19, it would have 20 neutrons in its nucleus. Option C is the right response.
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A man stands still on a moving walkway that is going at a speed of 0.2 m/s to
the west. What is the velocity of the man according to a stationary observer?
A. 0.2 m/s north
B. 0.2 m/s west
C. 0.2 m/s South
D. 0.2 m/s east
When,a man stands still on a moving walkway that is going at a speed of 0.2 m/s to the west,then the velocity of the man according to a stationary observer would be 0.2 m/s west,Therefore, the correct answer would be option B.
What is Velocity?The total displacement covered by any object per unit of time is known as velocity. The velocity of an object is depend on the magnitude as well as the direction of the object.
the mathematical expression for velocity is given by
velocity = total displacement /time
The speed and velocity of the object are very different from each other because speed does not depend upon the direction of the moving object but velocity depends on the magnitude of speed as well as the direction of the moving object.
As per given in the problem a man stands still on a moving walkway that is going at a speed of 0.2 m/s to the west therefore from the perspective of a stationary observer the velocity of man would be 0.2 m/s towards West.
Hence the correct options for the problem would be option B.
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can ya pls answer dis rq!
Answer:
I don't even know can u tell me how to ask questions
what is the relationship between electrostatic force and electric field?
in california the pacific plate slides past the north american plate. If the pcific plate is moving at a speed of 5 centimeters per year, how long will take for the plate to travel 100 meters
Answer:
6.34×10⁹ seconds
Explanation:
Applying,
V = d/t............. Equation 1
Where V = speed plate, d = distance covered by the plate, t = time it takes the plate to travel
make t the subject of the equation
t = d/V............ Equation 2
From the question,
Given: d = 5 cm/yr = (5×3.154×10⁻⁹) = 1.577×10⁻⁸ m/s, d = 100 meter
Substitute these values into equation 2
t = 100/1.577×10⁻⁸
t = 6.34×10⁹ seconds
Hence the time it takes the the plate to travel is 6.34×10⁹ seconds
If the box of 500N is placed over the land of area of 2m²,what pressure is experted by the box on the land?
Answer:
250 Pa or N/m^2
Explanation:
Pressure(P)=F/A=500/2=250 Pa or N/m^2
Diffraction spreading for a flashlight is insignificant compared with other limitations in its optics, such as spherical aberrations in its mirror. To show this, calculate the minimum angular spreading in rad of a flashlight beam that is originally 5.90 cm in diameter with an average wavelength of 610 nm.
Answer:
The answer is "[tex]1.2566 \times 10^{-5}\,rad[/tex]".
Explanation:
As per the Rayleigh Criterion the minimum angular spreading, for a circular aperture:
[tex]\theta_{\mathrm{min}}\approx \sin\theta=1.22\,\frac{\lambda}{d}[/tex]
[tex]\theta_{\mathrm{min}}=\mathrm{1.22\,\frac{\left( 610\,nm \right)}{\left( 5.90\,cm \right)}=1.22\,\frac{\left( 610\times10^{-9}\,m \right)}{\left( 5.90\times10^{-2}\,m \right)}}[/tex]
[tex]=1.22\times 103.389 \times 10^{-7}\\\\=1.22\times 1.03 \times 10^{-5}\\\\=\mathrm{1.2566 \times 10^{-5}\,rad}[/tex]
An astronaut is said to be weightlessness when he\she travels in a satellite. Does it mean that the earth does not attract him\her?
Answer:
Explanation:
The sense of weightlessness in orbiting satellite is because of the lack of any contact-forces. ... Thus, both the astronaut and the satellite have the same value of g, which is again equal to the centripetal acceleration of the satellite. These two neutralize each other, causing everything to appear weightless.
MAKE ME BRAINLIEST
30. The length of mercury thread when it is at 0°C, 100°C and at an unknown temperature 0 is 25mm, 225mm and 175mm respectively. What is the value of 02 A. 85.0°C B. 80.0°C C. 75.0°C D. 70.0°C
Answer:
75°C
Explanation:
175−25/225−25=x−0/100−0
150/200=x/100
x=150×100/200
= 75°C
The mass of an object is 4G and it has a density of 5gm^-3. what is the volume
Explanation:
Density is mass in grams over volume in cubic centimeters.
So it is
[tex]\frac{4g}{5cm^{-3} }[/tex] = 0.8 g/cm[tex]^{3}[/tex]
The unit is grams per cubic centimeter.
NB - density can also be kilograms over cubic meters
Two solid cubes have the same Mass but their edges are in the ratio of 4:1. What isthe ratio of their densities?
Let m be the mass of both cubes. If the smaller cube has side length x, then its volume is x ³. The side lengths of the larger cube have length 4x, so the larger cube's volume is (4x)³ = 64x ³, or 64 times as large as the smaller cube.
The first cube has a density of m/x ³, while the larger one has a density of m/(64x ³) = 1/64 m/x ³, so the ratio of densities is (1/64):1, or 1:64 (larger cube to smaller cube).
A car is running uniformly with the velocity of 72km/h3, what is its acceleration?
Answer: a =0
Explanation:
que tienen en común la materia y el sistema?
Answer:
La materia es la sustancia de la que está hecho todo material. En física, el sistema es una de las propiedades de la materia. Se puede transferir entre objetos y convertir en forma. No se puede crear ni destruir.
espero que te ayude!
if the velocity of a train starts from rest is 72km/h(20m/s) after 5 minutes, find out its acceleration and the distance travelled by the train in this time
Explanation:
Convert the time to seconds : 5minutes × 60 = 300seconds
Acceleration = Velocity / Time
Acceleration = 20m/s / 300s
Acceleration = 0.067m/s²
Distance = Velocity × Time
Distance = 20m/s × 300seconds
Distance = 6000m
When n resistance each of value x are connected parallel then resultant resistance x. When these n resistor connected in series. Total resistance
Answer:
Explanation:
Suppose you have 3 resistors each with a value of 3. If you placed them in parallel, would you get 3
1/3 + 1/3 + 1/3 = 1/r
The denominator doesn't change. So add the numerators.
(1 + 1 + 1)/3 = 3/3 = 1
So the question is faulty.
1 = 1/r
1*r = 1
r = 1/1
r = 1
define simple machine
Answer:
simple machine, any of several devices with few or no moving parts that are used to modify motion and the magnitude of a force in order to perform work. ... The simple machines are the inclined plane, lever, wedge, wheel and axle, pulley, and screw.
What is principle of liver??
Answer:
lever: Principle of the Lever
lever: Principle of the LeverIt has been found by experiment that two equal forces acting in opposite directions, i.e., clockwise and counterclockwise, and applied to a uniform lever at equal distances from the fulcrum counteract each other and establish a state of equilibrium, or balance, in the lever.
a sky driver jumps from an aircraft. the mass of sky driver sky driver is 70kg. state the equation linking weight,mass,and gravitional field strenght.
Answer:
Weight = Mass × Gravitational field strength
Explanation:
The mass of the skydiver = 70 kg
The weight of the skydiver, W, is given as follows;
W = m × g
Where-
g = The gravitational field strength ≈ 9.81 m/s²
Therefore, the equation linking weight mass and gravitational field strength is presented as follows;
Weight = Mass × Gravitational field strength
A horse is running on a circular path with constant speed but its direction is changing at every point. It is
Answer:
accelerating.
Explanation:
A horse is running on a circular path with constant speed but its direction is changing at every point. Thus, it is accelerating.
3. There is a bell at the top of a tower that is 45 m high. The bell weighs 64 kg. The
bell has joules of potential energy.
Answer:It has 8550 j energy
a boy jumps out of the bus . there is danger for him to fall:
a) towards moving bus
b)away from moving bus
c) in the directioin of motion
d) opposite to the direction of motion
Answer:
(B)
Explanation:
the boy will fall away from the bus if the bus is moving.
Calculate the acceleration of a train of mass 30 000 kg when driven by a force of 15000 N.
Answer:
Explanation:
F = ma, so filling in:
15000 = 30000a and
a = .50 m/s/s
The acceleration of a train is 0.50 [tex]m/s^{2}[/tex].
What is acceleration?Acceleration is the rate of change of the velocity of an object with respect to time.
F = ma
a = F/m
a = 15000/30000
a = 0.50 [tex]m/s^{2}[/tex]
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For Gerald the Human Cannonball, the gunpowder transforms and gives Gerald what type of energy?
Explanation:
The explosives changes Gerald the Human Cannonball and provides him with chemical energy.
Sulfur and carbon serve as fuels, whereas saltpetre serves as an oxidant. Gunpowder has long been employed as a propellant in weapons, artillery, rocketry, and fireworks, as well as a blasting ingredient in quarrying, mine, and road construction.
Calculate the force of gravitation between two objects of masses 50 kg and 120 kg respectively, kept at a distance of 10 m from one another.
Answer:
Answer
F=G×
d
2
m×M
m = 50 kg
M = 120 kg
Distance, d = 10 m
G=6.7×10
−11
Nm
2
/kg
2
F=6.67×10
−11
×
10
2
50×120
F=6.67×60×10
−11
F=4.02×10
9
N
Answer:
=4.002×10-⁷
Explanation:
(6.67×10-¹¹ ×50×120)/10²
=4.002×10-⁷
what is the relation between centre of gravity and stability
Explanation:
tilting it will raise the height of its center of gravity.
Even though you praise your dog for sitting inside on his bed and chewing the bone you gave him, your dog insists on going outside and burying his bone. This is MOST likely an example of:
Answer:
dog
Explanation:
Which of the following is true of highly conductive elements?
Answer:
A
Explanation:
i think a is the answer because if you take an example of group 1 and 2 metals on the periodic table you will notice that they are highly reactive but they have a few electrons in their outer most shells.
I hope this helps
20.In case the conductor is a heating appliance, then this energy(w) is converted into heat(H) i.e
A. w=H C. w=I2Rt
B. w=VIt D. all of above
Answer:
not sure just need points
Explanation:
a+b+c
(A) A triangular glass prism of thickness 12cm is placed on a mark on a piece of paper resting on a horizontal bench. If the refractive index of the material of the prism is 1.5, calculate the apparent displacement of the mark.
(B)Water is poured into a jar to a depth of 24cm. The bottom of the jar appears
to be raised by 6cm when viewed vertically. Calculate the refractive index of water.
Part A - The apparent displacement of the mark is 4 cm.
The refractive index of a material, n = real depth, D/apparent depth, L.
So, n = D/L
Since the refractive index of the triangular glass prism is 1.5, n = 1.5. Also, the triangular glass prism is 12 cm thick and placed on a mark on a piece of paper resting on a horizontal bench. So, the real depth of the mark on the piece of paper through the triangular prism is D = 12 cm and its apparent depth is L.
Since n = D/L,
making L, subject of the formula, we have
L = D/n
Substituting the values of the variables into the equation, we have
L = D/n
L = 12 cm/1.5
L = 8 cm
so, the apparent depth of the mark is 8 cm.
So, the apparent displacement of the mark is d = D - L = 12 cm - 8 cm = 4 cm
Thus the apparent displacement of the mark is 4 cm.
Part B - The refractive index of water, n = 1.33.
The refractive index of a material, n = real depth, D/apparent depth, L.
So, n = D/L
Since the depth of water in the jar is 24 cm, the real depth, D = 24 cm.
Also, the bottom of the jar appears to be raised by 6 cm. So, the apparent depth, L = 24 cm - 6 cm = 18 cm
Since n = D/L, the refractive index of water n = D/L
Substituting the values of the variables into the equation, we have
n = D/L
= 24 cm/18 cm
= 1.33
So, the refractive index of water, n = 1.33.
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Which of the following can be correct units for acceleration?
A. miles/hr/m
B. Km/s/hr
C. m/s/m
D. km/m/s
Answer:
B. Km/s/hr
Explanation:
the gravitational force between two masses at distance of 2.5×10^6 metre is 250 Newton . what should be distance between them to reduce the gravitational force by half?
Answer:
distance between should be 1.25 × 10^6 m
Explanation:
Force is proportional to separation distance.
[tex]250 \: newtons = 2.5 \times {10}^{6} \: metres \\ ( \frac{1}{2} \times 250) \: newtons = d \\ \\ d = \frac{125 \times 2.5 \times {10}^{6} }{250} \\ d = 1.25 \times {10}^{6} \: metres[/tex]
Answer:
distance between should be 1.25×10^6.
Explanation:
force Is proportional to separation .
mrk above answer branilest .
