Answer:
C. Increase in back emf
Explanation:
As the current through the field winding decreases the field strength also decreases and the back-emf is reduced, as a result the motor speeds up.
When the motor begins to speed-up, an additional back EMF is generated due to induction which reduces armature current. This also results in reduced strength of the field flux. The back emf generated is not enough to reduce the armature current which could stop the acceleration of the motor and the motor further accelerates.
A boy im50kg at rest on a skateboard is pushed by another boy who exerts a force of 200 N on him. If the first boy's
final velocity is 8 m/s, what was the contact time?
seconds
Answer:
Time, t = 2 seconds
Explanation:
Given the following data;
Mass, m = 50 kg
Initial velocity, u = 0 m/s (since it's starting from rest).
Final velocity, v = 8 m/s
Force, F = 200 N
To find the time, we would use the following formula;
[tex] F = \frac {m(v - u)}{t} [/tex]
Making time, t the subject of formula, we have;
[tex] t = \frac {m(v - u)}{F} [/tex]
Substituting into the formula, we have;
[tex] t = \frac {50(8 - 0)}{200} [/tex]
[tex] t = \frac {50*(8)}{200} [/tex]
[tex] t = \frac {400}{200} [/tex]
Time, t = 2 seconds
The picture below shows a person swinging a yo-yo in a circle. Which vector shows the velocity of the yo-yo at this moment?
A. B
B. A
C. C
D. D
Why does time have a direction? Please give your ideas I want to see them. Brainliest f0r most effort.:)
Answer:
it's a rule like water !!!!
Explanation:
Most importantly, time appears to run forward always never backwards. in other words there's perceived arrow of time and there's thermodynamic arrow of time, and they always point in a forward direction
for every system there are more states that seem chaotic then states that seem ordered.
the arrow of time seems to have something to do with that tendency. but to get from one instance to another where things get more entropy, we already need some kind of time, gotta admit that.
some (physicists) believe that time is an illusion, that the whole universe is already set in stone, like a block (the idea is therefore called block universe). from the perspective of a godlike outside observer the universe would be like a book, or a 4D movie. the characters might feel a movement of things in a direction, but rewinding it wouldn't feel different in any instance because the order in wich things happen is already written.
a different idea is that there are infinite many different futures and the further they are away, the less we can know for sure about them in a physical way. and this might also be work for the past, so that different parts could lead to one present.
when macroscopic information is deleted, it might not be reversible, so the past gets ultimately blurry. one example for deletion of macroscopic information this is the Library of Alexandria wich burned down.
all the quantum information is still conserved, but the order of things (like letters on pages) is lost and could have been in different configurations before. we can't ultimately not even see the past, as much as we would try.
personally the idea that the past is written in stone but the future is in flux doesn't make any sense for me. because than I could have free will now, but not from the perspective 10 days later.
the present would be a very special thing than, the stage where the universe likes to play.
maybe we can get a grasp on time if we look at it like rules for a game, like a cardboard game.
To get from one configuration to the next ,we must follow rules. like throwing dice and moving in monopoly.
gravity would be a simple real world example for such a rule, a natural law.
But no one would have a firm clue where this rules came from.
TLDR: I don't know and neither does anyone else for sure, not even top notch scientists.
the hardest questions are easy to formulate, but maybe even impossible for us to answer in a satisfying way. I hope we will understand those hard questions better one day, and maybe even get answers.
at which point is the Kinetic energy the lowest?
Answer:
the lowest kinetic energy point is option D
What is photosynthesis???
photosynthesis, the process by which green plants and certain other organisms transform light energy into chemical energy. During photosynthesis in green plants, light energy is captured and used to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds.[tex]\pmb{ }[/tex]
What do you think Jose’s grandmother meant by saying that the bread was too dense? What other things can you think of that are “dense”?
Answer:
What I think that Jose's grandmother meant by saying that the bread was too dense is that she thinks the bread is too heavy or it can even mean to be too compacted in substance. The matter in the bread are close together and not spread out like in the air, when the matter in the air starts to come closer together it starts to make fog, because it is becoming more dense. Some more things that are heavy or dense are things like a big stereo speaker, an anvil, or even a big piece of wood used to build.
Explanation:
the unit of energy is same as that of work i.e joule give reason
"Energy" is the ability to do work.
"Work" is the process of using energy.
A car travelling at 10ms ,acceleration uniformly at 2ms what will be its velocity after 5s?
[tex]we \: know \: that \\ acceleration = \frac{(final \: velocity - initial \: velocity)}{time} \\ = > a = \frac{(v - u)}{t} \\ = > 2m {s}^{ - 2} = \frac{{(v - 10m {s}^{ - 1} })}{5s} \\ = > 2m {s}^{ - 2} \times 5s = v - 10m {s}^{ - 1} \\ = > 10m {s}^{ - 1} = v - 10m {s}^{ - 1} \\ = > 10m {s}^{ - 1} + 10m {s}^{ - 1} = v \\ = > 20m {s}^{ - 1} = v \\ = > 20m {s}^{ - 1} = initial \: velocity[/tex]
Hope it helps!!
Thanks!!
Answer:
20 ms
Explanation:
You know
acceleration=2ms initial Velocity=10ms Time=5s
We are finding Final V
Use the equation Final v = (a x t) + initial v
2 x 5 = 10
10 + 10 = 20
Does this equation show that transmutation has taken place during decay?
Why or why not?
Ni – S.Ni+y
A. No, because there is conservation of the number of atoms as well
as the number of nucleons.
B. No, because high-energy electromagnetic waves are emitted.
C. Yes, because the numbers of nucleons and atoms are conserved.
D. Yes, because nickel atoms remain nickel atoms with the same
number of neutrons.
Answer:
Maybe A is the correct answer
E
How does the construction of dams positively affect natural resources?
by providing water for irrigation and restoring trees to areas where forests once existed
by creating reservoirs, preventing flooding, and renewing destroyed ecosystems
by preventing flooding, creating reservoirs, and providing water for irrigation
by renewing destroyed ecosystems and restoring trees to areas where forest once ersted
Answer:
by preventing flooding, creating reservoirs, and providing water for irrigation
Dams and waterways store and provide water for irrigation so farmers can use the water for growing crops. This idea goes way back into history. Irrigation is an important part of using water. In areas where water and rain are not abundant (like the desert), irrigation canals from rivers and dams are used to carry water.
Dams help in preventing floods. They catch extra water so that it doesn’t run wild downstream. Dam operators can let water out through the dam when needed.
Connected to a battery that offers a d.d.p. of 3.0Volts, we have the four lamps, all identical with resistances equal to 2.0 Ohms. The association appears in the figure. Note that the switch is open, so it doesn't pass current in the circuit (it's like an off switch). When the key closes, the lamps come on. Determining the Req of the association and the total current flowing through the circuit, we will find:
Answer:
Option D. 5Ω e 0.6 A
Explanation:
1. Determination of the equivalent resistance.
We'll begin by calculating the equivalent resistance of resistor B and resistor C. This can be obtained as follow:
Resistor B (R₆) = 2 Ω
Resistor C (R꜀) = 2 Ω
Equivalent Resistance (R₆꜀) =?
R₆꜀ = R₆ × R꜀ / R₆ + R꜀ (parallel connection)
R₆꜀ = 2 × 2 / 2 + 2
R₆꜀ = 4 / 4
R₆꜀ = 1 Ω
Finally, we shall determine the equivalent resistance of the circuit. This can be obtained as follow:
Resistor A (Rₐ) = 2 Ω
Equivalent resistance of resistor B and C (R₆꜀) = 1 Ω
Resistor D (Rₔ) = 2 Ω
Equivalent Resistance (R) =?
R = Rₐ + R₆꜀ + Rₔ (series connection)
R = 2 + 1 + 2
R = 5 Ω
Thus, the equivalent resistance of the circuit is 5 Ω
2. Determination of the total current in the circuit.
Potential difference (V) = 3 V
Equivalent resistance (R) = 5 Ω
Total current (I) =?
V = IR
3 = I × 5
Divide both side by 5
I = 3 / 5
I = 0.6 A
Thus, the total current in the circuit is 0.6 A
Summary:
Equivalent resistance = 5 Ω
Current = 0.6 A
Option D gives the current answer to the question.
why is oil denser than air
Answer:
The molecules of oil are more packed together than those of air.
What is pulling force? Give any two examples.,
Answer:
Push or Pull Forces - example
When you push against a wall the force that you exert is an example of a push force. When you pull a trolley car the force that you exert is an example of pull force.
Complete the sentence-
Friction always acts
1 along the direction of the motion.
2 opposite to the motion.
3 both of these.
4 none of these.
Answer:
Friction always acts opposite to the motion.
what is the value of acceleration due to gravity at the equatorial region of the earth
Answer:
9.78 m/s^2
Explanation:
Acceleration due to gravity at equator is 9.78m/s^2
Liquid to solid with explanation on the basis of kinetic model and freezing point.
Answer:
As a liquid is cooled its molecules lose kinetic energy and their motion slows. When they've slowed to where intermolecular attractive forces exceed the collisional forces from random motion, then a phase transition from liquid to solid state takes place and the material freezes.
hope this helps you..!!!!What kind of waves are present during an earthquake?
Answer:
There are four main types of earthquake waves:
P-waves S-waves (which are body waves), Rayleigh waves Love waves (which are surface waves).HOPE IT HELPS!!
How much current flows in the circuit if two resistors of 6 connected in parallel are
supplied with potential difference of 12 volts?
Answer:
4 A
Explanation:
Firstly we need to calculate the equivalent resistance. Since, two resistors of 6 connected in parallel, so equivalent resistance will be given by,
[tex]\longrightarrow[/tex] 1/R = 1/R1 + 1/R2
[tex]\longrightarrow[/tex] 1/R = (1/6 + 1/6) Ω
[tex]\longrightarrow[/tex] 1/R = (1 + 1)/6 Ω
[tex]\longrightarrow[/tex] 1/R = 2/6 Ω
[tex]\longrightarrow[/tex] R = 6/2 Ω
[tex]\longrightarrow[/tex] R = 3 Ω
We know that,
[tex]\longrightarrow[/tex] V = IR
V denotes p.d (12V)I denotes currentR denotes resistance (3 Ω)[tex]\longrightarrow[/tex] 12 = I × 3
[tex]\longrightarrow[/tex] 12 ÷ 3 = I
[tex]\longrightarrow[/tex] 4 Ampere = I
What happens to the electric force between two particles if the distance
between them is doubled?
A. It decreases to half the original force.
B. It increases to twice the original force.
C. It increases to 4 times the original force.
D. It decreases to 1/4 of the original force.
Answer:
D.
Explanation:
Force and distance are inversely related, so a greater distance results in a weaker force.
If the resistance is 25 and the voltage is 75. What is the amount of current that I will be getting?
Answer:h
Explanation:
Put the steps of the scientific method in order
Suppose that you are standing on a train accelerating at 0.20g (where g is the acceleration due to gravity). What minimum coefficient of static friction must exist between your feet and the floor if you are not to slide
Answer:
0.2
Explanation:
The given parameters are;
The acceleration of the train, a = 0.2·g
The mass of the person standing on the train = m
Let μ represent the coefficient of static friction, we have;
The force acting on the person, F = m × a = m × 0.2·g
The force of friction acting between the feet and the floor, [tex]F_f[/tex] = m·g·μ
For the person not to slide we have;
The force acting on the person = The force of friction acting between the feet and the floor
F = [tex]F_f[/tex]
∴ m × 0.2·g = m·g·μ
From which we get;
0.2 = μ
The coefficient of static friction that must exist between the feet and the floor if the person is not to slide, μ = 0.2.
Let's first consider the dynamics behind the motion in this video. After the student releases the wheel by cutting the cord, what forces are acting on the wheel
Answer:
Hello. You did not provide the video to which the question refers, however, given the context of your question, we can consider that the forces acting on the wheel are the weight of the wheel, the tension that this weight promotes on the rope and the normal force of the axle.
Explanation:
According to the context of the question, we can see that the wheel is being pulled by a rope. The weight of the wheel is the first force that acts on it, promoting resistance to the impulse that the rope promotes on the wheel. When this wheel is pulled by the rope, the weight of the wheel creates tension in the rope, which stretches and becomes tensioned in response to this force. However, this tension is also a force acting on the wheel, as is the normal force on the axis between these two elements.
An athlete runs around a circular track of radius 50 m and finishes at the same point where he began his journey. His total displacement in metre(s) is evaluated to be
Answer:
Explanation:
His displacement is 0 because he ended up exactly where he started.
One type of atomic particle that is found in the nucleus does not contribute to
an element's atomic number. What are two characteristics of this type of
atomic particle?
Answer:
1) They are electrically neutral
2) They have slightly more weight than protons
Explanation:
The given atomic particle found in the nucleus has the following characteristics;
The location of the particle = The nucleus
The (numbers of the) particle does not contribute to (change) the atomic number of the element
The particles found within the nucleus of an atom are; Neutrons and protons
The particle within the nucleus that determines the atomic number = The number of protons
Therefore, the particle referenced in the question is the neutrons
The two characteristics of the neutron are;
1) The neutrons are neutral, electrically
2) Neutrons have slightly more weight than protons
3) Neutrons are magnetic
4) Neutrons are very small
5) Neutrons consist of three quarks; One 'Up', and two 'Down' quarks
Therefore, two characteristics of the particle are;
1) They are electrically neutral and 2) They are slightly heavier than protons.
what is kepler's law??
➜what is kepler's law??
[tex]\huge\red{\boxed{\huge\mathbb{\red A \pink{N}\purple{S} \blue{W}\orange{ER}}}}[/tex]
Kepler gave the three laws or theorems of motion of the orbitals bodies
[tex]{\huge {\bold{ \red{ \star}}}}{ \blue{ \bold{FIRST \: \: \: LAW}}}[/tex]
This law state that the celestial bodies revolves around the stars in elliptical orbit and star as a single focus.
Example :- Earth revolves around the Sun as assuming it as single focus
This also shows that earth revolves around the sun in elliptical orbit.
[tex]{\huge {\bold{ \blue{ \star}}}}{ \green{ \bold{SECOND \: \: \: LAW}}}[/tex]
Area covered by the planet is equal in equal duration of time irrespective of the position of the planet.
It also states that Angular momentum is constant
As Angular momentum is constant it means areal velocity is also constant.
[tex]\frac{ \triangle \: A}{ \triangle \: T} = \frac{L}{2m}△T△A=2mL[/tex]
where:-
A is the area.
T is the time.
L is the angular momentum.
M is the mass of the body.
[tex]{\huge {\bold{ \green{ \star}}}}{ \purple{ \bold{THIRD \: \: \: LAW}}}[/tex]
square of the time of the revolution is directly proportional to the cube of the distance between the planet and star in Astronomical unit.
[tex]{T}^{2} = {a}^{3}T2=a3[/tex]
where:-
T = time of revolution
a is the distance between the planet and star.
[tex]\purple\star \: {Thanks \: And \: Brainlist} \blue \star \\ {\orange{ \star}}{if \: U \: Like d \: My \: Ans} {\green{ \star }}[/tex]
A mass that weighs 8 lb stretches a spring 24 in. The system is acted on by an external force of 4 sin 4t lb. If the mass is pulled down 6 in. and then released, determine the position of the mass at any time. Determine the first four times at which the velocity of the mass is zero
Answer:
[tex]t = \frac{\pi}{8}, \frac{\pi}{4}, \frac{3\pi}{8}, \frac{3 \pi}{4}[/tex]
Explanation:
The equation of force is
F = 4 sin 4 t
Compare with the standard equation
f = A sin wt
where, w is the angular frequency and A is the amplitude.
Now
w = 4 rad/s
Let the time period is T.
the relation for the time period is
[tex]T = \frac{2\pi}{w}\\\\T = \frac{2 \pi}{4}\\\\T = \frac{\pi}{2}[/tex]
the time period is defined as the time taken by the body to complete one oscillation.
So, the velocity is zero at the extreme points where the object is at time, T/4 and its odd T/2, 3T/4, 3T/2, etc.
So, the velocity is zero at time
[tex]t = \frac{\pi}{8}, \frac{\pi}{4}, \frac{3\pi}{8}, \frac{3 \pi}{4}[/tex]
If you are driving 90 km/hkm/h along a straight road and you look to the side for 2.8 ss , how far do you travel during this inattentive period
Answer:
Distance = 70 meters
Explanation:
Given the following data;
Speed = 90 km/h
Time = 2.8 seconds
Conversion:
90 km/h to meters per seconds = 90 * 1000/3600 = 90000/3600 = 25 m/s
To find the distance covered during this inattentive period;
Speed can be defined as distance covered per unit time. Speed is a scalar quantity and as such it has magnitude but no direction.
Mathematically, speed is given by the formula;
[tex]Speed = \frac{distance}{time}[/tex]
Making distance the subject of formula, we have;
[tex] Distance = speed * time [/tex]
Substituting into the above formula, we have;
[tex] Distance = 25 * 2.8 [/tex]
Distance = 70 meters
Un móvil recorre una trayectoria en línea recta de 6000 metros y demora 30 minutos. ¿Cuál es su rapidez expresada en Km/h?
Answer:
La rapidez del móvil es 12 kilómetros por hora.
Explanation:
Asumamos que el móvil experimenta un movimiento rectilíneo uniforme, cuya ecuación cinemática es la siguiente:
[tex]v = \frac{x}{t}[/tex] (1)
Where:
[tex]x[/tex] - Distancia recorrida, en kilómetros.
[tex]t[/tex] - Tiempo, en horas.
[tex]v[/tex] - Rapidez, en kilómetros por hora.
Si tenemos que [tex]x = 6000\,m[/tex] y [tex]t = 30\,min[/tex], entonces la rapidez del móvil es:
[tex]v = \frac{6000\,m\times \frac{1}{1000}\,\frac{km}{m}}{30\,min \times \frac{1}{60}\,\frac{h}{min} }[/tex]
[tex]v = 12\,\frac{km}{h}[/tex]
La rapidez del móvil es 12 kilómetros por hora.
A cylindrical container closed of both end has a radius of 7cm and height of 6cm A.)find the total surface area of the container B.) find the volume of the container
