An electromagnet is a device that uses an electric current to produce a magnetic field.

Electromagnets are typically composed of a piece of metal wrapped with wire and connected to a battery. The battery provides the electric current, and the loops or coils of wire enhance the magnetic field. The more loops there are, the stronger the magnetic field.

When electric current flows through the electromagnet, the metal core becomes magnetized, so it possesses a north pole and a south pole.

Motors place electromagnets inside of permanent magnets as shown below.



However, motors are designed so that the polarity of the electromagnet constantly flips. That is, the north pole becomes the south pole, and the south pole becomes the north pole, every time the electromagnet turns 180 degrees.

Why is it designed this way?
A.
to conserve the energy in the battery
B.
to constantly polarize the field magnet
C.
so the electromagnet will continuously turn
D.
so the magnetic field will get stronger

Answer: Moisture and food (bread)

Explanation:

Mould grows best in humid, damp air/wet conditions.

Since the bread is moist it will provide humidity for the mould as well as food.

A container with a cover would not be a favoring condition as mould needs oxygen to grow and survive.

Answer:

The tank appears to be 3 m deep only. Step by step solution by experts to help you in doubt clearance & scoring excellent marks in exams.

Answer:

t = 125 seconds

Explanation:

Given that,

The mass of a train, m = 50,000 kg

Initial speed, u = 5 m/s

Stopping force, F = 2000 N

We know that,

Force, F = ma

Where

a is acceleration

[tex]F=\dfrac{m(v-u)}{t}\\\\t=\dfrac{m(v-u)}{F}\\\\t=\dfrac{50000(0-5)}{-2000}\\\\t=125\ s[/tex]

So, it will take 125 seconds to stop the car.

Answer:

3 gm / cm^3

Explanation:

Density = weight / volume

90 / 30 = 3 gm/cm^3

Answer:

C: 3.93 x 10^22 free electrons

Explanation:

The no. of free electrons can be found out using the following formula:

[tex]N = V\rho\\[/tex]

where,

N = No. of free electrons = ?

V = Volume = 2.55 cm³

ρ = density of electrons = 1.54 x 10²² free electrons/cm³

Therefore, using these values in the equation, we get:

[tex]N = (2.55\ cm^3)(1.54\ x\ 10^{22}\ free\ electrons/cm^3)\\[/tex]

N = 3.93 x 10²² free electrons

Therefore, the correct option is:

C: 3.93 x 10^22 free electrons

Answer:

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Answer:

Explanation:

It can cause  damage to the blood vessels.  It Can cause  heart failure, vision loss, stroke, kidney disease, and other health problems.

Hope this helps!!!

Answer:

True, wheel and excel has co-axial cylinder. true or false.

You can follow me to get more answer.

Answer:

true

Explanation:

yes they have two com xial cylinder and they work together

Answer:

Una rueda de 20 cm de radio gira de modo que en dos minutos ... Datos: • Radio 20 cm = 0,2 m • Tiempo = 2 min 30 s= 150 s • N° de vueltas ... m • f = 300 rpm = 5 Hz • Período • T = 1 f = 1 5 = 0,2 s • Rapidez angular ... 160 rpm (frecuencia de la rueda 2) • 10 * 160 = 80 * y donde y = 20 rpm

Explanation:

Miniature circuit breakers is called the developed form of fuse because MCBs are more sensitive to current than fuses. They immediately detect any abnormality and switch off the electrical circuit automatically. This prevents any permanent damage to electrical appliances and human beings

Answer:

a)   v = 0,  a = - 15 pi²

b) v = - 40.8 cm / s,  a = -74.2 cm / s

Explanation:

the simple harmonic motion is described by the expression

        x = A cos (wt + Ф)

in that case they indicate the amplitude of the movement

        A = 15 cm

angular velocity and period are related

        w = 2π / T

         w = 2π/ 2

         w = π rad / s

speed is defined by

         v = dx / dt

          v = -A w sin (wt + Ф)

acceleration is defined by

         a = dv / dt

         a = - A w² cos (wt + Ф)

In order to evaluate this expression we must know the value of the phase constant (Ф) that meets the initial conditions, the most common thing is that the system is released, v = 0 for y = 0 s, let's use the speed equation

          v = -A w sin (0+ Ф)

for this expression to be zero, the sine must be zero, so

         Ф= 0

now let's write the equations for our case

         v = - 15 π sin (π t)

         a = - 15 π² cos (π t)

a) for x = 0

          v = 0

          a = - 15 pi²

b) for x = 7.5 cm

Let's find out how long it takes to get to this position

          x = 15 cos (π t)

          7.5 / 15 = cos π t

          pi t = cos⁻¹ 0.5

          t =  1.047/π

don't forget that the angles are in radians

          t = 0.333 s

now let's look for speed and acceleration

         v = - 15 π sin (π 0.333)

         v = - 40.8 cm / s

         a = - 15 π² cos (π 0.333)

         a = -74.2 cm / s

Answer:

Conditions under which the belt and pulleys are operating – The friction between the belt and pulley may decrease substantially if the belt happens to be muddy or wet, as it may act as a lubricant between the surfaces.

Explanation:

I hope that this would be helpful

first. this is only worth 38 points second it's B

Answer:

Explanation:

Answer:

The apparent power is the power delivered to a load without considering the effects of the power-factor angle of the load

Explanation:

If I and V are the current and voltage across the load, the apparent power, = IV

Since,

apparent power = active power + reactive power

active power = IVcosФ

reactive power = IVsinФ

So, IV = IVcosФ + IVsinФ

where I = current, V = voltage and Ф = power factor angle.

We see that the apparent power is the product of the current, I and the Voltage, V without considering the power factor angle of the load.

So, the apparent power is the power delivered to a load without considering the effects of the power-factor angle of the load.

Answer:

f nothing can move faster than spped of light.

Explanation:

Solution :

Crust

In the field of geology, the crust may be defined as the outermost solid shell of a planet. It forms the topmost outer hard layer of the earth surface. Earth has three layers. They are the crust, mantle and the core.

When we go deeper and deeper inside the earth's crust, the temperature rise. In the crust, on the surface of the earth, the temperature is normal and is atmospheric. As we go deep down the core, the temperature rise and it is highest at the core where all the rock and the iron is in the form of the molten lava.

According to the Geologist, beneath the earth's crust, for every mile we go inside the temperature rises by 15 degree Fahrenheit.

Answer:

The system has two solutions:

(1, -1) and (0, 0)

Explanation:

We have the system of equations:

x + y = 0

x = x^2 + 2*x*y

To solve this, the first step is to isolate one of the variables in one of the equations, I will isolate x on the first one.

x = -y

Now we can replace this on the other equation, to get:

x = x^2 + 2*x*y

(-y) = (-y)^2 + 2*(-y)*y

Now we can solve this equation for y.

-y = y^2 - 2*y^2

-y = -y^2

y^2 - y = 0

We can solve this using the Bhaskara's formula:

The solutions are then:

[tex]y = \frac{-(-1) \pm \sqrt{(-1)^2 - 4*1*0} }{2*1} = \frac{1 \pm 1}{2}[/tex]

Then the two possible solutions are:

y = (1 + 1)/2 = 1

and

y = (1 - 1)/2 = 0

Suppose that we take the first one, y = 1.

Then the solution for x is given by "x = -y"

Then:

x = -1

This means that one solution of the system is (-1, 1)

If we take the other solution for y, y = 0

The value of x will be:

x = -y = -0 = 0

Then another solution of the system is (0, 0)

Answer:

dissociation of acetic acid (like vinegar) in water

Explanation:

CH3COOH is basically vinegar (aka acetic acid)

dissociation of acetic acid in water

so when you put vinegar in water it makes 2 hydrogen ions (H+) and acetate ( CH3C00 ) a chemical that used in making film

Answer:

kilogram metre per second square

Answer: The height of rollercoaster cart above the ground is 1.53 m.

The velocity of rollercoaster cart is 5.29 m/s.

Explanation:

Potential energy is the energy occupied by a substance due to its position. Formula for potential energy is as follows.

P.E = mgh

where,

m = mass of substance

g = gravitational constant = [tex]9.8 m/s^{2}[/tex]

h = height

Substitute the values into above formula as follows.

[tex]P.E = m \times g \times h\\67500 J = 4500 kg \times 9.8 m/s^{2} \times h\\h = \frac{67500 J}{4500 kg \times 9.8 m/s^{2}}\\= 1.53 m[/tex]

Hence, the height of rollercoaster cart above the ground is 1.53 m.

Kinetic energy is the energy occupied by the motion of a substance. Formula for kinetic energy is as follows.

[tex]K.E = \frac{1}{2}m \times v^{2}[/tex]

where,

m = mass of substance

v = velocity of substance

Substitute the values into above formula as follows.

[tex]K.E = \frac{1}{2}m \times v^{2}\\63000 J = \frac{1}{2} \times 4500 kg \times v^{2}\\v^{2} = \frac{63000 J \times 2}{4500 kg}\\v = 5.29 m/s[/tex]

Hence, the velocity of rollercoaster cart is 5.29 m/s.

Answer:

Nylon is a generic designation for a family of synthetic polymers composed of polyamides.

Explanation:

Answer:

The most widely accepted theory for the formation of fossil fuel is that fossil fuel was formed over time from decaying organic matter. Organisms died and were buried in the ground millions of years ago.

Explanation:

g00gle answer! so change it up a little :P

hope this helps :)

Answer:

No. Neither the USGS nor any other scientists have ever predicted a major earthquake. We do not know how, and we do not expect to know how any time in the foreseeable future. USGS scientists can only calculate the probability that a significant earthquake will occur in a specific area within a certain number of years.

Answer:

No. Neither the USGS nor any other scientists have ever predicted a major earthquake. We do not know how, and we do not expect to know how any time in the foreseeable future. USGS scientists can only calculate the probability that a significant earthquake will occur in a specific area within a certain number of years.

Explanation:

Answer:

Mass (m) = 5.4 kg

Force (f) = 20 N

Acceleration (a) = ?

Acceleration= m × a

[tex]m \times a \\ = 5.4 \times 20 \\ = 108 \: ms ^{ - 2} [/tex]

=> The resulting acceleration of the object is 108 m/s².

By compressing the spring a distance x (in m), you are storing 1/2 k x ² (in J) of potential energy, which is converted completely into kinetic energy 1/2 m v ², where

• k = 40 N/m = spring constant

• m = 10 kg = mass of the ball

• v = 2 m/s = ball's speed (at the moment the spring returns to its equilibrium point)

So we have

1/2 k x ² = 1/2 m v ²

x = √(m/k v ²) = √((10 kg) / (40 N/m) (2 m/s)²) = 1 m

Answer:

b is the correct answer

Explanation: