Please I need help kindly answer it fast.

The following statement “a varistor is a two-terminal device which primarily changes in resistance as the temperature changes” is False.

A varistor is a two-terminal device that primarily changes its resistance in response to changes in voltage, not temperature. Varistors are voltage-dependent resistors, also known as voltage-dependent or voltage-sensitive resistors (VDRs). They are designed to protect electronic circuits from overvoltage conditions by acting as voltage clamps.

Varistors have a high resistance at normal operating voltages, but their resistance decreases significantly when the voltage exceeds a certain threshold, known as the "clamping voltage." They are made from semiconducting materials, usually metal oxide compounds such as zinc oxide, and their resistance characteristics are nonlinear, meaning the resistance decreases exponentially with increasing voltage.

When a varistor is subjected to excessive voltage, it starts conducting current, shunting the excess voltage away from the sensitive components of a circuit and preventing damage. Once the voltage returns to normal levels, the varistor's resistance returns to its high state.

Therefore, varistors primarily respond to changes in voltage, not temperature.

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Big has no cause of action against Temper. In this scenario, while Temper may have made a verbal threat and raised his fists in a confrontational manner, there is no indication that he physically touched or harmed Big.

Assault refers to the act of intentionally causing apprehension or fear of imminent harmful or offensive contact. Battery, on the other hand, involves the intentional and harmful or offensive physical contact with another person without their consent.

In this case, Temper's actions may constitute assault due to the verbal threat and raising his fists, creating an atmosphere of fear or apprehension. However, since no physical contact or harm occurred, battery is not applicable. Therefore, the appropriate response is option d: Big has no cause of action against Temper.

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Sound travels at approximately 343 meters (or 1,125 feet) per second in dry air at room temperature.

To determine how far away lightning is when thunder sounds 10 seconds after the lightning flash, we can use the speed of sound.

Distance = Speed × Time

Distance = 343 m/s × 10 s

Distance = 3,430 meters

Therefore, if thunder sounds 10 seconds after the lightning flash, the lightning is approximately 3,430 meters (or 3.43 kilometers) away.

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Answer:

The angle of refraction is \(\sf 74.7 \textdegree\)

Explanation:

In this example we can use Snell's law to evaluate the angle of refraction.

\(\sf n_1 \sf \sin \theta_1 \sf = n_2 \sin \theta_2\)

Where

\(\sf n_1\) is the is the index of refraction of the first medium (incident index)

\(\sf n_2\) is the is the index of refraction of the second medium (refracted index)

\(\sf \theta_1\) is the angle of incidence

\(\sf \theta_1\) is the angle of refraction

I am assuming the ray of light travels from air to glass.

Numerical Evaluation

In this example we are given

\(\sf n_1=1.52\)

\(\sf \theta_1=39.4 \textdegree\)

The refractive index of air is 1.000293. So we can say

\(\sf n_2=1.000293\)

Substituting our values into the equation yields

\(\sf 1.52 \cdot \sin 39.4=\sf 1.000293\cdot \sin \theta_2\)

Lets solve for \(\theta_2\).

\(\dfrac{\sf 1.52 \cdot \sin39.4}{1.000293} =sin\ \theta_2\\\)

\(\dfrac{\sf 0.96479038}{1.000293} =sin\ \theta_2\\\)

\(\sf 0.96450777=sin\ \theta_2\\\)

\(\sf \arcsin \left(0.96450777\right)=\theta_2\)

\(74.68922535=\theta_2\)

Rounding to the nearest tenth leaves us with

\(\theta_2 =74.7\)

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Static stretches are those in which you remain in a single position—standing, sitting, or lying still—for up to 45 seconds. Dynamic stretches are regulated motions that get your ligaments, muscles.

Movement is included into dynamic stretches, such as lunges with a torso twist. As opposed to dynamic stretches, static stretches include holding a stretched position for a while. Stretches that are static include the triceps stretch and the butterfly stretch.

A swimmer might, for instance, circle their arms before entering the water. A series of movements to get the body moving before engaging in any kind of exercise can also be considered dynamic stretches.

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A 40 kg crate is pulled at a constant velocity. The coefficient of kinetic friction is 0.5 and the crate moves 7 m . The amount of work done is 140 joule.

When an object is moved over a distance by an external force, at least a portion of that force must be applied in the direction of the displacement.

By multiplying the length of the path by the component of the force acting along the path, work can be calculated if the force is constant. The work W is equal to the force f times the distance d, or W = fd, to mathematically describe this idea.

The work is W = fd cos if the force is applied at an angle of to the displacement. Performing work on a body involves moving it in its entirety from one location to another as well as.

Therefore, A 40 kg crate is pulled at a constant velocity. The coefficient of kinetic friction is 0.5 and the crate moves 7 m . The amount of work done is 140 joule.

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Answer:360 kg m/s

Explanation:Momentum refers to an object's quantity of motion.

Formula for Momentum: p=mv

p = refers to the momentum

m = refers to the object's mass (this is represented by the unit kg or kilogram)

v = this refers to the object's velocity (this is represented by the unit m/s or meter per second)

So, given that the bike has a mass of 18 kg and is traveling at 20 m/s, then you can already get the momentum by multiplying both of these values.

p = the bike's momentum (what is being asked here)

m = 18 kg

v = 20 m/s

Thus, p = 18kg × 20 m/s = 360 kg m/s

The bike's momentum is 360 kg m/s.

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Answer:

The planes’ acceleration from A to B is 500m/s^2

Explanation:

Given that the initial velocity u is 8000m/s

and also given the final velocity v=10,000 m/s

the time taken to move from A to B = 40 second

The acceleration is defined as the rate of change of velocity with time

we know that the expression for acceleration is given as

a=(v-u)/t

substituting our given data into the expression for a we have

a=(10000-8000)/40

a=2000/40

a=500m/s^2

The planes’ acceleration from A to B is 500m/s^2

The frequency of the girl's bell heard by her dad is approximately 772 Hz.

1. This problem involves the Doppler effect, which describes how the frequency of a sound wave changes when the source of the sound is moving relative to an observer.

When the source is moving towards the observer, the frequency appears higher, and when the source is moving away from the observer, the frequency appears lower.

We can use the following equation to calculate the frequency of the sound wave heard by the dad:

f' = f(v + vd) / (v - vs)

where f is the frequency of the sound wave emitted by the girl, v is the speed of sound in air, vd is the speed of the dad's car (33.4 m/s), and vs is the speed of the girl on her bicycle (8.54 m/s). f' is the frequency heard by the dad.

Substituting the given values, we get:

f' = f(v + vd) / (v - vs)

f' = 714 Hz * (343 m/s + 33.4 m/s) / (343 m/s - 8.54 m/s)

f' = 772 Hz

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When the ball is kicked, there is now an unbalanced force that acts on the ball thereby impacting an acceleration.

We know that according to Newton's laws, an object would remain in its state of rest or a state of uniform motion unless it is acted upon by an external force. This is also known as the law of inertia.

As the ball is kept on the ground, there are two forces that act on the ball;

1) The weight of the ball that act downwards

2) The reaction force on the ball that acts upwards

The two forces are balanced hence the ball remains on the ground.

When the ball is kicked, there is now an unbalanced force that acts on the ball thereby impacting an acceleration.

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Answer:

When the ball is kicked, there is now an unbalanced force that acts on the ball thereby impacting an acceleration.

Explanation:

What are unbalanced forces?

We know that according to Newton's laws, an object would remain in its state of rest or a state of uniform motion unless it is acted upon by an external force. This is also known as the law of inertia.

As the ball is kept on the ground, there are two forces that act on the ball;

1) The weight of the ball that act downwards

2) The reaction force on the ball that acts upwards

The two forces are balanced hence the ball remains on the ground.

When the ball is kicked, there is now an unbalanced force that acts on the ball thereby impacting an acceleration.

Answer:

i believe the answer is c

Answer:

Explanation:

Remark

The only thing that might trip you up is what to do with the angle. The vertical component of the 15 degrees does no work against anything. So the 15 degrees limits the horizontal force.

The formula is

Work = F * d * cos(15)

The givens are

F = 2000 N

d = 30 m

Cos(15) = 0.9659

Solution

Work = 2000 * 30 * cos(15)

Work = 57,955

Rounded to two places would be 5.8 * 10^4

C

Zinc and cadmium have photoelectric work functions given by WZn=4.33eV and WCd=4.22eV, respectively.  the maximum kinetic energy of photoelectrons from zinc surface is 0.54 eV and from cadmium surface is 0.70 eV.

The maximum kinetic energy (KEmax) of photoelectrons is given by:

KEmax = hν - W

where h is Planck's constant, ν is the frequency of the incident light, and W is the work function of the material.

To calculate the frequency of the incident light, we use the formula:

c = λν

where c is the speed of light.

Substituting the given values, we get:

ν = c/λ = (3.00 x 10^8 m/s)/(270 x 10^-9 m) = 1.11 x 10^15 Hz

Using this value of ν, we can now calculate the maximum kinetic energy of photoelectrons for each surface:

For zinc (Zn):

KEmax = hν - WZn = (6.63 x 10^-34 J s)(1.11 x 10^15 Hz) - 4.33 eV = 0.54 eV

For cadmium (Cd):

KEmax = hν - WCd = (6.63 x 10^-34 J s)(1.11 x 10^15 Hz) - 4.22 eV = 0.70 eV

Therefore, the maximum kinetic energy of photoelectrons from zinc surface is 0.54 eV and from cadmium surface is 0.70 eV.

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Answer:

Charles's law

Explanation:

Answer:

m=1225kg

Explanation:

Use p=mv

24500=m(20m/s)

24500/20=1225kg

The acceleration of the rocket of mass 17250 kg when pushed with a thrust of 7236904 N is 409.73 m/s².

Acceleration can be defined as the rate of change of velocity

To calculate the acceleration of the rocket, we use the formula below, And this formula is obtained from newton's second law of motion.

Formula:

Where:

Make a the subject of the equation

From the question,

Given:

Substitute these values into equation 2

Hence, The acceleration of the rocket is 409.73 m/s².

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Answer:

the same number of electron shells

Explanation:

If you could somehow return to the Earth in many millions of years, you would find a very different planet than the one we know today.

Some of the most significant changes would include:

- The continents would be in different positions:

The Earth's crust is constantly moving, and over millions of years, the continents will have shifted significantly.

For example, the Atlantic Ocean is currently widening, while the Pacific Ocean is shrinking. This means that in millions of years, the Americas will be much further away from Europe and Africa than they are today.

- The climate would be different:

The Earth's climate is constantly changing, and over millions of years, it is likely that there will have been significant shifts in temperature and precipitation patterns. This could mean that some areas that are currently deserts might be covered in forests, while other areas that are currently lush and green might be dry and barren.

- The species of plants and animals would be different:

Evolution is a constant process, and over millions of years, many species will have evolved, while others will have gone extinct. This means that the plants and animals you see on the Earth in millions of years will be very different from the ones that are here today.

- The appearance of the Earth would be different:

Over millions of years, the Earth's surface is constantly being reshaped by processes like erosion, volcanic activity, and tectonic movement. This means that the mountains, valleys, and other features of the Earth's surface will be very different in millions of years than they are today.

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Answer:

revolution of the planets around the Sun.

Explanation:

The revolution of the planets around the Sun is a result of the gravitational force exerted by the Sun. The Sun's gravitational pull attracts the planets, causing them to move in an elliptical orbit around it. This motion is known as the revolution of the planets around the Sun. The other options listed (rotation of the planets on their axes, rotation of the Moon on its axis, and revolution of the Moon around Earth) are also related to motion and gravity, but they are different phenomena.

The strong man accelerates the boulder of mass 264 kg at 4.1 m / s² if he uses a force of 2452 N.

W = m g

W = Weight

m = Mass

g = Acceleration due to gravity

m = 264 kg

g = 9.8 m / s²

W = 264 * 9.8

W = 2587.2 N

F = 2452 N

W = Normal force, N = 2587.2 N

\(f_{k}\) = μ N

\(f_{k}\) = Kinetic frictional force

μ = Co-efficient of kinetic friction = 0.53

\(f_{k}\) = 0.53 * 2587.2

\(f_{k}\) = 1371.22 N

∑ \(F_{x}\) = m a

F - \(f_{k}\) = m a

2452 - 1371.22 = 264 * a

a = 1080.78 / 264

a = 4.1 m / s²

Therefore, the strong man accelerates the boulder at 4.1 m / s²

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Answer:

A

Explanation:

a is the answer to your question.

The RMS current , Power and Maximum voltage have values 0 to 1 , V1/2 to 0 and infinity to zero.

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Yes, it is possible for an object to experience a net zero external unbalanced force. This means that the forces acting on the object are balanced, resulting in no overall force acting on it. An object can be in a state of rest or continue moving with a constant velocity when it experiences a net zero external unbalanced force.

When an object experiences a net zero external unbalanced force, it can be in different states:
If the object is at rest and experiences a net zero external unbalanced force, it will remain at rest. This occurs when the forces pushing or pulling on the object in different directions cancel each other out. For example, if you push an object with a force of 50 N to the right, and someone else pulls it with an equal force of 50 N to the left, the object will not move.
If the object is in motion and experiences a net zero external unbalanced force, it will continue to move with a constant velocity. This happens when the forces pushing or pulling on the object are equal in magnitude and opposite in direction. For instance, if a car is traveling at a constant speed of 60 km/h and experiences an equal resistance force due to air resistance, the net force on the car is zero, and it will continue moving at the same speed.
It's important to note that even though the net external unbalanced force is zero, the object may still experience internal forces, such as gravitational or frictional forces, which do not cancel out.

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Therefore, the orbital speed of the satellite that orbits at an altitude of one Earth radius above the surface of the Earth is 7.91 x 103 m/s.

When an object orbits around the Earth, it is influenced by two forces: gravity and centrifugal force. The gravitational force is directed towards the center of the Earth, while the centrifugal force is directed away from the center of the Earth, and it is perpendicular to the gravitational force.

Therefore, these two forces balance each other, and the object follows an elliptical orbit around the Earth.

The period of the orbit is the time that the object takes to complete one full revolution around the Earth.

The speed of the object depends on the radius of the orbit, and the mass of the Earth.

The formula to calculate the speed of the object is given by:

v = √(G M / r)

where: v is the speed of the object, G is the gravitational constant, M is the mass of the Earth, r is the radius of the orbit.

The value of G is 6.67 x 10-11 N m2 / kg2

The mass of the Earth is 5.97 x 1024 kg

The radius of the orbit is equal to the sum of the radius of the Earth and the altitude of the satellite, which is one Earth radius above the surface of the Earth.

Therefore, the radius of the orbit is:

r = 6.37 x 106 m + 6.37 x 106 m = 1.27 x 107 m

Substituting the values in the formula:

v = √(6.67 x 10-11 N m2 / kg2 x 5.97 x 1024 kg / 1.27 x 107 m)

v = 7.91 x 103 m/s

This is the speed required for the satellite to remain in orbit around the Earth.

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In summary, the observations about determining ages of rocks and fossils are based on scientific principles such as radioactive decay, superposition, and original horizontality.

A scientific principle is a fundamental concept or law that explains how the natural world works. It is a statement based on empirical evidence and repeated observations that is widely accepted by the scientific community as a fundamental truth. Scientific principles provide a framework for understanding and explaining natural phenomena, and they form the basis for scientific research and discovery.

Examples of scientific principles include:

The law of conservation of energy, which states that energy cannot be created or destroyed, only transformed from one form to another.

The theory of evolution, which explains how species change over time through natural selection and genetic variation.

The law of gravity, which explains the attraction between objects with mass and their impact on space-time.

The principle of relativity, which explains how the laws of physics are the same for all observers in uniform motion relative to each other.

Scientific principles are subject to change and refinement as new evidence and discoveries are made, but they provide a reliable foundation for scientific inquiry and understanding.

Here,

1. Observations about determining ages of rocks and fossils:

Scientists use a variety of methods to determine the ages of rocks and fossils, such as radiometric dating, relative dating, and stratigraphy.

Radiometric dating involves measuring the decay of radioactive isotopes in rocks or fossils, which provides an estimate of the time elapsed since the material was last heated or exposed to sunlight.

Relative dating involves comparing the ages of rocks or fossils based on their position in relation to one another.

Stratigraphy involves studying the layers of rock or sedimentary deposits to determine the relative ages of the materials.

2. Explanation based on scientific principles:

Radiometric dating is based on the principle of radioactive decay, which is the spontaneous breakdown of atomic nuclei into smaller particles over time. The rate of decay is constant, which allows scientists to use the amount of remaining radioactive material to estimate the time elapsed since the material was last heated or exposed to sunlight.

Relative dating is based on the principle of superposition, which states that the oldest rocks or fossils are found at the bottom of a sequence, while the youngest rocks or fossils are found at the top. By comparing the ages of rocks or fossils in different layers, scientists can determine their relative ages.

Stratigraphy is based on the principle of original horizontality, which states that sedimentary layers are deposited in horizontal layers. By studying the layers of rock or sedimentary deposits, scientists can determine the relative ages of the materials based on their position.

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Answer:Deforestation refers to the decrease in forest areas across the world that are lost for other uses such as agricultural croplands, urbanization, or mining activities. Greatly accelerated by human activities since 1960, deforestation has been negatively affecting natural ecosystems, biodiversity, and the climate. The UN’s Food and Agriculture Organization estimates the annual rate of deforestation to be around 1.3 million km2 per decade.

Explanation:

The negative effect of deforestation on the environment is desertification. The correct option is B.

Desertification is the process by which fertile land becomes desert, typically as a result of drought, deforestation, and inappropriate agriculture or land use practices. It occurs when land that was once able to support vegetation and life becomes increasingly dry, barren, and unable to sustain crops, livestock, or human populations. This can be due to natural causes such as prolonged droughts, but it is often exacerbated by human activities such as deforestation, overgrazing, and soil degradation. Desertification can have devastating effects on the environment, leading to soil erosion, loss of biodiversity, and reduced productivity of the land. It can also cause social and economic problems, such as displacement of people, food shortages, and conflicts over resources.

Here in the question,

Deforestation is the clearing of trees and other vegetation from an area, leading to the loss of habitat and biodiversity, and disruption of water cycles. It can also cause soil erosion, which can result in the depletion of soil nutrients, reduced productivity, and eventually lead to desertification. Additionally, deforestation contributes to climate change by releasing carbon dioxide into the atmosphere, which can cause global warming and other environmental problems. Habitat restoration, soil production, and urbanization are not negative effects of deforestation but can be impacted by it.

Therefore, The correct answer is B i. e Desertification.

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The velocity of the car when it began coasting was approximately 17.2 m/s.

If a car is coasting without any external force acting on it (such as friction), then its initial kinetic energy is converted entirely into potential energy as it moves uphill. Therefore, we can use the principle of conservation of energy to solve this problem.

The principle of conservation of energy states that the total energy of a closed system (in this case, the car and the Earth) remains constant over time. Therefore, the initial kinetic energy of the car is equal to the potential energy gained as it moves uphill. Mathematically, we can express this as:

1/2 mv^2 = mgh

where:

m = mass of the car

v = initial velocity of the car when it began coasting

g = acceleration due to gravity (9.8 m/s^2)

h = height gained by the car (15 m)

We can simplify this equation by canceling out the mass (m) on both sides:

1/2 v^2 = gh

Substituting the given values, we get:

1/2 v^2 = 9.8 m/s^2 * 15 m

v^2 = 2 * 9.8 m/s^2 * 15 m

v = √(2 * 9.8 m/s^2 * 15 m)

v ≈ 17.2 m/s

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Answer:

mercury is more dense

Explanation:

Explanation:

Iron ball sinks in water but not in mercury because of the difference in the density iron used in iron ball. The iron ball has more density than water and less than the mercury.

Hence, Iron ball sinks in water but not in mercury.

-TheUnknownScientist

Answer:

a = 2.84 m/s²

Explanation:

Given that,

Net force, F = 2500 N

Mass of the car, m = 880 kg

We need to find the acceleration of the car. Net force is given by :

F = ma

\(a=\dfrac{F}{m}\\\\a=\dfrac{2500\ N}{880\ m/s^2}\\\\a=2.84\ m/s^2\)

So, the acceleration of the car is 2.84 m/s².