How many revolutions does the motor shaft turn through between the time when the current is reversed and the instant when the angular velocity is zero
Answer:it equals 0
Explanation:hope this is a good answer
Angular velocity is the ratio of angular displacement to time. Then the number of turns by the shaft is zero.
What is angular velocity?The rate of change of angular displacement is called angular velocity. It is a vector quantity.
We know that the angular velocity formula
[tex]\rm Angular \ velocity = \dfrac{Angular \ displacement}{time}[/tex]
The motor shaft turns through between the time when the current is reversed and the instant when the angular velocity is zero.
Then the number of turns will be
[tex]\rm Number \ of\ turns = Angular \ velocty \times time \\\\Number \ of\ turns = 0 *time \\\\Number \ of\ turns = 0[/tex]
The number of turns by the shaft is zero.
More about the Angular velocity link is given below.
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the second law of thermodynamics imposes what limit on the efficiency of a heat engine?
A heat engine cannot have a thermal efficiency of 100% For all reversible processes, the second-law efficiency is 100%. The second-law efficiency of a heat engine cannot be greater than its thermal efficiency. The second-law efficiency of a process is 100% if no entropy is generated during that process
Elements in the periodic table are arranged in order of increasing...
A mass number
B.Number of protons
C. number of neutrons
D. number of nucleons
Answer:
(B) The number of protons - only the number of protons in the nucleus determines the element - mass and neutrons can vary for the same element
What can cause matter to change from one state to another?
a change in its temperature
a change in its pressure
both a and b
neither a nor b
un cuerpo suspendido en el aire es capaz de:
a) liberar energía al caer
b) puede ejecutar un trabajo
c) posee energía antes de caer
d) todas son correctas
Answer:
Explanation:
d
Find the work done while lifting a 115 kg sofa 1.5 m off the ground.
Find the weight first
P= 10m = 10 x 115 = 1150 N
work done while lifting a 115 kg sofa 1.5 m off the ground :
A= Ph = 1150 x 1.5 = 1725 J
P/s: I think the weight first is 115kg
ok done. Thank to me :>
When riding your bike, you come up to a small child who jumps in front of you. You slam on the brakes, and your bike comes to a sliding stop. Which force greatly increases when you lock the brakes and slide
Answer: friction :)
Explanation:
I took the test and got 100%
how do mechanical waves compare with electromagnetic waves?
Answer:
Electromagnetic waves are waves that have no medium to travel whereas mechanical waves need a medium for its transmission. Electromagnetic waves travel in a vacuum whereas mechanical waves do not. The mechanical waves need a medium like water, air, or anything for it to travel.
Explanation:
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Which statement about a converging lens is not correct?
A ray parallel to the principal axis of the lens is refracted through the principal focus.
B All rays of light refracted by the lens pass through the principal focus.
C The distance between the centre of the lens and the principal focus is the focal length
D The principal focus of the lens is a point on the principal axis.
Geometric optics allows you to find which the correct answer about which false statement is:
B) All rays of light refracted by the lens pass through the principal focus.
Geometric optics studies the formation of images using the light geometric properties of optical systems, the main expression for this is:
[tex]\frac{1}{f} = \frac{1}{p} + \frac{1}{q}[/tex]
Where f is the focal length, p and q the distance to the object and the image respectively.
There are some points of special interest:
Object at infinity (p = ∞). In this case of the expression we see that the image is at the focal length. Image at infinity (q = ∞). In this case the object is at the focal point.
Let's analyze the claims.
A) True. A parallel ray comes from infinity and the image is formed at the focal point.
B) False. The image point is given by the expression above and depends on the distance to the object.
C) True. This is the definition of focal length.
D) True. All distances are measured from the main axis.
In conclusion, using geometric optics we can find that the correct answer about which false statement is:
B) All rays of light refracted by the lens pass through the principal focus.
Learn more about geometric optics here: brainly.com/question/2548694
A galaxy spectrum has a redshift of 70,000 km per second. If the Hubble constant is 70 km per second per Mpc (megaparsec), how far away from us in this galaxy
Using the Hubble law v = H₀d where v = recessional speed = 70,000 km per second H₀ = hubble constant = 70 km/s/Mpc and d = distance of galaxy.
Making d subject of the formula, we have
d = v/H₀
Substituting the values of the variables into the equation, we have
d = v/H₀
d = 70000 km/s/70 km/s/Mpc
d = 1000 Mpc
So, the galaxy is 1000 Mpc away from us.
Learn more about hubble law here:
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please solve due is today....asap please
Answer:
a)object is in uniform motion
Explanation:
velocity is constant.and a=0
body is in uniform motion.
BRAINLIST PLS
consider two vectors A and B Where A-B and |A+B|=|A-2B| vector B is directed in the positive x_direction and A makes an angle of 60°above the positive x_axis find magnitude of the two vectors
Answer:
It should be mentioned that an efficient way to work this vector addition problem is with the cosine law for general triangles (and since
a
,
b
and
r
from an isosecles triangle, the angles are easy to figure). However, in the interest of reinforcing the usual systematic approach to vector addition, we note that the angle
b
makes with the +x axis is 30
0
+105
0
=135
0
(a) The x component of
r
x
=(10.0m)cos30
0
+(10.0m)cos135
0
=1.59m
(b) the y component of
r
is r
y
=(10.0m)sin135
0
= 12.1 m.
(c) the magnitude of
r
is r = ∣
r
∣=
(1.59m)
2
+(12.1m)
2
=12.2m
(d) The angle between
r
and the +x direction is tan
−1
[(12.1m)/(1.59m)]=82.5
0
Explanation:
Andrew skis down a hill.
Andrew starts from the top of the hill and his speed increases as he goes downhill.
He controls his speed and direction by using his skis.
He brings himself to a stop at the bottom of the hill.
Describe the energy changes that happen between starting and stopping.
Explanation:
gravitational potential energy at the top of the hill, which transforms into kinetic energy as he moves bottom of the hill
that's mean potential energy transfoms into kinetic energy
His potential energy is converted into kinetic energy when his speed increases as he goes downhill.
What is mechanical energy?Mechanical energy is the combination of all the energy in motion represented by total kinetic energy and the total potential energy stored energy in the system which is represented by total potential energy.
Total mechanical energy is s the sum of all the kinetic as well as potential energy stored in the system.
ME = KE + PE
When Andrew skis down a hill then he had stored potential energy due to the height of the hill and his gravitational weight,
Due to the height of the slope and his weight, Andrew had potential energy stored when he skied down it.
As he descended the hill, his speed increased, transforming this potential energy into kinetic energy.
Learn more about mechanical energy from here,
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A body moving with constant acceleration covers the distance between tu point 60m apart in 5s. Its velocity as it passes the second point is 15m/s. What is the acceleration?
Please find attached photographs for your answer.
Hope it helps.
Do comment if you have any query.
What time is the lunar eclipse tonight in california?
negatively charged particles of radiation emitted from the decay of radioactive substances are known as
Answer: beta particles
Explanation:
that's the answer
A 2.3 kg ball has 76 J of kinetic energy. How fast is it moving? Show all work and use correct units of measurement for the answer to get full credit.
Answer:
8.13 m/sExplanation:
The kinetic energy of an object can be found by using the formula
[tex]k = \frac{1}{2} m {v}^{2} \\ [/tex]
m is the mass in kg
v is the velocity in m/s
To find the velocity we make v the subject of the equation
That's
[tex]v = \sqrt{ \frac{2k}{m} } \\ [/tex]
From the question
k = 76 J
m = 2.3 kg
We have
[tex]v = \sqrt{ \frac{2 \times 76}{2.3} } = \sqrt{ \frac{152}{2.3} } \\ = 8.129388...[/tex]
We have the final answer as
8.13 m/sHope this helps you
If a car is at rest, which of the following is correct?
A.not enough information
B.more than 3 forces are acting on the car
C.no force acts on the car
D.The net force on the car is zero
Answer:
D
Unbalanced or net forces acting on the car will cause it to move
The correct answer is option D. The net force on the car is zero.
What forces act on a car at rest?
Since the car is not accelerating, the force of air resistance and the friction force must add to give the exact opposite of the applied force. The net force here would be zero, as well.
When an object is at rest no gravitational force is acting on it?Newton's First Law is the law of inertia. An object with no net forces acting on it which is initially at rest will remain at rest. If it is moving, it will continue to move in a straight line with constant velocity.
Learn more about Newton's First Law here: https://brainly.com/question/11472821
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a person would weigh less on Mercury than on planet blank because blank
Answer:
Earth because of greater gravity
a ______ is a push or pull that acts on an object
Answer:
A force is a push or pull that acts on an object.
:)
Answer:
force
Explanation:
It's unit is in Newton
What is the acceleration of a 20 kg backpack lifted with a force of 15 N?
a. 0.75 m/s2
b. 1.33 m/s2
c. 300 m/s2
d. 5 m/s2
The answer is option A. 0.75 m/s^2
the formula needed to solve this is acceleration = force/mass
we know the following:
mass of the backpack = 20KG
the force is 15N
therefor- acceleration = 15/20
which can also be written as 3/4, leaving us with the final answer of .75 m/s^2
Answer:
0.75 m/s2
Explanation:
0.75 m/s2
Kichelle enjoys balloon animals from the carnival. She just received a balloon giraffe that has an initial temperature of 39.0°C and a volume of 1.28 L. If Preston plays a trick on Kichelle, and puts her balloon giraffe into the freezer, what would be the new volume of the balloon if the temperature drops down to 8.0°C?
39°C=1.28L
8°C=? Less
=8°C/39°C×1.28L
=8/39×1.28L
=10.24/39
=512/195
=2.6L
Question 5: A heavy rope is flicked upwards, creating a single pulse in the rope. Make a drawing of the rope and indicate the following in your drawing
a. the direction of motion of the pulse
b. Amplitude
c. Pulse length
d. Position of the rest
Answer:
the direction of motion of the pulse
UV light has ______ wavelengths than visible light waves, and its peak energy is at a wavelength of ______.
Explanation:
Shorter wavelength since UV light has more energy than visible light
365 nm - What is the peak energy wavelength of UV light? It allows both infrared daylight and ultraviolet night-time communications by being transparent between 320 nm and 400 nm and also the longer infrared and just-barely-visible red wavelengths. Its maximum UV transmission is at 365 nm
Please help me calculate this question along with the equation
Hi there!
We can use the following:
U (Gravitational Potential Energy) = mgh
m = mass of object (kg)
g = acceleration due to gravity OR gravitational field strength
h = height, or displacement (m)
ΔU = Uf - Ui, so:
Uf = 3 × 1.5 × 10 = 45 J
Ui = 3 × 0 × 10 = 0
ΔU = Uf - Ui = 45 - 0 = 45 J
1 point
What is the potential energy of a 12543 kg tank this on the ground? (only
put the number, no units or commas) *
Answer:
PE=0
Explanation:
If the tank is on the ground, there is 0 height which means the equation of PE=mh will be PE=12543(0)=0, hope this helps!
your field of study in college is called your________.
Answer:
Majors are also called concentrations. An academic major or concentration is a college or university student's main field of specialization during his or her associates or undergraduate studies which would be in addition to, and may incorporate portions of, a core curriculum.
A taxi is travelling at 20 m/s. Its driver accelerates with acceleration 5 m/s2 for 4 s. What is its new velocity?
Please find attached photograph for your answer.
Hope it helps.
Do comment if you have any query.
Describe the forces that make a bicycle move.
Answer:
this is an example of Newton's Second Law, acceleration happens when a force acts on a mass.
the force that makes the bicycle move is your foot pushing against the pedal
I'LL MARK YOU BRAINLIST!!
ali starts moving his car from rest and accelerates it at 5 m/s^2 over 8 seconds. what is the velocity of ali's car reached by the end of these 8 seconds ?
Explanation:
u=0, v=?, a=5m/s², t=8sec
So, by the formula,
v=u+at
v=0+5×8
v=40m/s.
hope this helps you .