a jeweler is wearing a 20 d magnifying lens directly in front of his eye. if his near point is a typical 25 cm, how close can he hold a gem that he is inspecting?

Answer:

A metal is an element which is typically hard, shiny, fusible, malleable, and ductile, with good electrical and thermal conductivity. A nonmetal is an element that does not have the properties of a metal. A metalloid is an element having intermediate properties of both metals and nonmetals.

This happens because the sound waves bunch up when the train is moving toward the crossing and the frequency appears to be higher. When the train moves away from the crossing, the sound waves are spread out and the frequency appears to be lower than its actual frequency.

The Doppler Effect describes the apparent change in the frequency of sound waves (or light waves) due to the relative motion of the source and the observer. When a train approaches a crossing, the sound waves from the whistle are compressed due to the movement of the train towards the observer, resulting in a higher pitch of the whistle.

As the train passes by, the sound waves from the whistle get stretched due to the movement of the train away from the observer, resulting in a lower pitch of the whistle. This phenomenon is known as the Doppler Effect. This happens because the sound waves bunch up when the train is moving toward the crossing and the frequency appears to be higher. When the train moves away from the crossing, the sound waves are spread out and the frequency appears to be lower than its actual frequency.

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Answer:

Topographic maps give the user the ability to view a three-dimensional landscape on a two-dimensional map. One who is able to read a topo map can identify the elevation and location of valleys, peaks, ridges, and other land features.

Explanation:hope this helps

Block Diagram: The block diagram is an important tool for the analysis and design of feedback control systems. In this diagram, the closed-loop system consists of a forward gain element and a feedback loop. The input signal (applied voltage) is modified by the gain element and the output signal (orientation of the test stand) is fed back to the input of the gain element via the feedback loop. The intermediate signals are labelled as follows:

INPUT SIGNAL: The input signal is the applied voltage.

OUTPUT SIGNAL: The output signal is the orientation of the test stand.

FEEDBACK SIGNAL: The feedback signal is the output signal that is fed back to the input of the gain element through the feedback loop. The feedback signal is subtracted from the input signal to generate an error signal.

ERROR SIGNAL: The error signal is the difference between the input signal and the feedback signal. The error signal is multiplied by the gain element to generate the output signal.

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Answer:

satellite B

Explanation:

A .F= G (mM)/r²

B .F= G (2mM)/r² = 2G (Mm)r²

C .F= G (3mM)/(2r)² = ¾G (mM)/r²

D .F= G (4mM)/(2r)² = G (mM)/r²

Answer:

R = V^2 sin 2 θ / g        range formula

R is a maximum for θ = 45 and R = V^2  g

g = V^2 / R = 3^2 / 15 = .6 m/s^2

Answer:

B. The volume of an object is the same as the

weight of that object.

Explanation:

Every thing else is right and that one is wrong.

Answer:

B. The volume of an object is the same as the

weight of that object.

Explanation:

i hope it helps

It is true that a magnetic force must be exerted on the charge carriers in a conducting loop for the current to be induced in the loop.

Magnetic Force refer to force that attract or repel between electrically charged particles mainly because of their movement. This force is responsible for attraction of magnets.

The force on a conduction current loop in a uniform magnetic field is always zero. A current loop with magnetic moment pointing to the left magnitude decrease to the right.

Therefore, It is true that a magnetic force must be exerted on the charge carriers in a conducting loop for the current to be induced in the loop.

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Answer:

According to Newton's Second Law of Motion :    

Where,

F = Force Applied

m = Mass of the object

a = Acceleration

Now, we will use this law to solve this question.

Given :

Acceleration or a = 15.3 m/s²

Force = 44 N

Mass = ?

Substitute, the given values in the formula.

F = ma

⇒ m = F/a

   m = 44/15.3

m = 2.9 kg

Answer:

7.0 n

Explanation:

The Torque is only produced when the force is applied perpendicular to the moment arm.

The equal and opposite force acting at a point from the axis of rotation is called the moment.

M = F x r

Moment of force is also called as Torque.

Moment arm is the distance of the point of application of force from the axis of rotation of the body.

Thus, the perpendicular component only, produces the torque.

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The statement given "Galileo's early telescopes revealed the four large moons of Jupiter, the rings of Saturn, and its large moon Titan." is true because Galileo's early telescopes revealed the four large moons of Jupiter, the rings of Saturn, and its large moon Titan.

Galileo Galilei, an Italian astronomer, made significant observations using his early telescopes. His observations provided evidence to support the heliocentric model of the solar system proposed by Copernicus. With his telescope, Galileo discovered four large moons orbiting Jupiter, which are now known as the Galilean moons: Io, Europa, Ganymede, and Callisto. He also observed and documented the presence of rings around Saturn and identified its largest moon, Titan. These observations revolutionized our understanding of the solar system and provided critical evidence for the heliocentric model.

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Answer:

d = 2 [m].

Explanation:

To solve this problem we must use the principle of conservation of energy, where the mechanical energy in a state plus the work done on the body, must be equal to the mechanical energy in the state E. This can be easily represented in the following equation.

\(E_{A}+W_{A-E}=E_{E}\)

where:

Ea = Mechanical energy in A [J]

Wa-e = Work among states a and e [J]

Ee = Mechanical energy in E [J].

The key to being able to understand this problem is that in state A, we only have kinetic energy, while the energy in state E is equal to zero (there is no movement). The work is equal to the product of force by distance, as work acts in the opposite direction to movement, this has a negative sign.

\(10 - F*d = 0\\5*d = 10\\d = 10/5\\d = 2 [m]\)

At point a, the intensity level of the sound emitted uniformly in all directions from a small source of sound is 60.0 db, and the distance from the source is 3.20 m.

The intensity level of sound is a measure of the power of the sound waves per unit area, and it is measured in decibels (db). The intensity level of sound decreases with distance from the source due to the spreading of sound waves in all directions. In this case, the sound source is emitting sound waves uniformly in all directions, so the intensity level at point a is the same as the average intensity level at all points that are 3.20 m from the source. The intensity level of sound is related to the distance from the source by the inverse-square law, which states that the intensity of sound waves decreases with the square of the distance from the source.

In other words, if the distance from the source is doubled, the intensity level decreases by a factor of four. Therefore, if we move twice as far away from the source, the intensity level will be reduced by 6 db (since 6 db is approximately the difference in intensity level between two points that differ by a factor of two in distance).To find the intensity of the sound at point A, which is 3.20 meters away from the source and has an intensity level of 60.0 dB, we first need to use the decibel formula.

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The method the astronomer needs to find the distance is the hubble law.

The hubble law states that galaxies are moving away from at earth at speeds proportional to their distance.

The hubble law is expressed mathematically as v = H₀d where v = recessional speed, H₀ = Hubble constant and d = distance of galaxy from earth.

The recessional speed of the galaxy is found from the redshift of the light emitted from the galaxy.

Since we are dealing with a globular cluster of stars, the recessional speed is found from the redshift of the light emitted from the globular cluster of stars.

If we determine the recessional speed, we can then determine the distance of the globular cluster of stars by making the distance subject of the formula in the equation.

So, d = v/H₀

So, the method the astronomer needs to find the distance is the hubble law.

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Answer:

The answer is A

Explanation:

I have had this question before

hope this helps!! <3

The one that is not a way in which life is dependent on photosynthesis is that helping in cure of diseases. The correct option is C.

Photosynthesis is a technique that plants as well as other lifeforms use to transform light energy into chemical energy that can then be released to fuel the organism's activities via cellular respiration.

Photosynthesis' primary function is to convert solar energy into chemical energy and then store that chemical energy for later use. This process powers the majority of the planet's living systems.

Photosynthesis is essential to all living things because it is the primary source of oxygen in the atmosphere.

Without photosynthetic activity, the carbon cycle would not have been possible, oxygen-requiring life would perish, and plants would perish.

Due to photosynthesis, the organisms breathe in the oxygen, sugar is used as a food, and also helps to lower down global warming.

Thus, the correct option is C.

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The apparent brightness of Star A compared to Star B will be much lower. This is due to light diminishing in intensity over distance.

Star A is four times further from the Earth than Star B, so its luminosity is emitted out over a larger surface area, resulting in a much dimmer appearance when viewed from Earth. To understand this better, consider the inverse-square law. This law states that the light from a star, given its magnitude and distance to Earth, will be inversely proportional to the square of its distance to Earth.

This implies that as a star moves away, its light will be spread over a much larger area and therefore its apparent brightness will diminish, even if its absolute luminosity remains unchanged. Therefore, even though Star A is four times as luminous as Star B, its apparent brightness when viewed from Earth will be much lower.

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If a system has 46.5 j of heat added to it, and the system does 75.5 j of work on its surroundings. 29 j is the change in the internal energy of the system.

Internal energy refers to the energy that exists within the system. It is represented by the letter "U" in English.

Thermal energy is another name for internal energy. It is the energy of a substance as a result of the kinetic and potential energies connected to the ad hoc motion of all the constituent particles.

Internal energy, which is measured in KJ or Joule, is the energy attributed to the chaotic arrangement or random motion of particles within the system. Using the formula for internal energy, we can calculate the same.

The difference between the heat flow in a system and the work done by or on the system (PV) equals the change in internal energy, and the change in internal energy formula aids in calculating the same.

Energy Equation within the energy of the universe is constant, in accordance with the basic law of thermodynamics.

Additionally, the sum of the work done and the heat transported is equal to the change in a system's internal energy.

Additionally, the sum of the change in the system's internal energy and the work performed by the PV system equals the heat added or flown.

The Change in Internal Energy Formula is:

                    ΔU  =  Q  +  W

Here,

U =  the total change in internal energy within the system

Q =  the heat exchanged between a system and its surroundings (outside the system)

W  =  work done by or on the system

                 =  46.5 - 75.5

                 = 29j

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Answer:

Wave a is louder than wave b!!!

Explanation:

Yes

Answer:

By Lenz's law, for, coils, if he North pole is activated on the electromagnet, the pole on the side of the coil closest to the electromagnet will be a North pole and the flow of the current will be counter clockwise

Explanation:

Lenz's law states that where a changing magnetic field induces an electric current in a solenoid, the magnetic field that is produced by the coil opposes the initial activation of the electromagnet in the solenoid

By Flamings right hand rule, we have;

Therefore, by Lenz's law, for, coils, if he North pole is activated on the electromagnet, the pole on the side of the coil closest to the electromagnet will be a North pole and the flow of the current will be counter clockwise.

When a comet like Hale-Bopp comes closest to the Sun in its orbit, we say that it is at perihelion. Explanation:Comets are celestial objects that travel around the Sun in an elliptical orbit.

The perihelion is the point at which a comet's orbit is closest to the Sun, whereas the aphelion is the point at which it is farthest from the Sun. The speed of the comet varies as it moves around the Sun, reaching its maximum at perihelion and slowing down as it approaches aphelion. The term perigee refers to the point in a comet's orbit when it is closest to Earth, whereas the term apogee refers to the point when it is farthest away from Earth. The escape velocity refers to the minimum speed that an object needs to escape the gravitational pull of a massive body.

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From the mathematical form of Newton's Law of Gravity, the force of gravity goes up as:  the distance decreases

From the mathematical form of Newton's Law of Gravity, the force of gravity between two objects can be expressed as:

\(F = G * \frac{(m_1 * m_2)}{r^2}\)

Where:

F is the gravitational force between the objects,

G is the gravitational constant (a fixed value),

\(m_1\) and \(m_2\) are the masses of the objects, and

r is the distance between the centers of the objects.

Based on this equation, we can deduce the following:

So, to summarize, the force of gravity increases when either object's mass increases or when the distance between the objects decreases. Conversely, the force of gravity decreases when either object's mass decreases or when the distance between the objects increases.

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Answer:

What happens is that light slows down when it passes from the less dense air into the denser glass or water. This slowing down of the ray of light also causes the ray of light to change direction.

Explanation:

A cylindrical bit of graphite with a radius of 0.7 mm is subjected to a potential differential of 24 V along its length by the student.

Pencils, lubricants, crucibles, casting facings, polishes, arc lights, batteries, electric motor brushes, and nuclear reactor cores all include graphite. China, India, Brazil, N.korea, and Canada all mine large amounts of it. Graphite was inadvertently created for the first time by Edward G.

It is special in that it possesses traits common to both metals and non-metals, including flexibility without being elastic, high thermal and electrical conductivity, high refractoriness, and chemical inertness. Due to its low X-ray and neutron absorption, graphite is a particularly useful material.

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Answer:

165.529454

Explanation:

According to the Pythagorean Theorem for calculating the lengths of a right angle triangle's sides, a^2 + b+2 = c^2, where c is the longest side (and the side opposing the right angle). So in your case it would be 150*150 + 70*70 = 27400. And √ 27400 is your answer.

Answer:

4. 1. 2. 3.

Explanation:

The potential energy here is gravitational potential energy which is the equation mgh. m = mass, g = gravity (9.8) h = height. With this we can solve each of the given cases. 1. would turn out to be 784, 2. 1176, 3. 9800 and 4. 245. We can then compare which one is smallest and that would go first. In this case 4. So the order from least to greatest is 4. 1. 2. 3.

Answer:

A Wheel and Axle

Explanation:

Answer:

B. by blending in with the trees

Answer:

B. by blending in with the trees

Explanation:

The estimated potential at point P (4,5,6) taking V = 0 V at (0,0,0) is 12.204 V.

Electric potential at point P due to a point charge q is given as; V=kq/r Where V is the electric potential, q is the charge of the particle producing electric potential, k is the Coulomb's constant and r is the distance between the point charge and the point where electric potential is to be determined.  At point P (4,5,6), the distance from the point charge of 10nC to P is given as;

√[(4−2)^2+(5−10)^2+(6−3)^2] = √54 = 7.348m.

So, the potential due to the point charge at point P is;

V1=kq/r1 = 9×10^9 × 10 × 10^−9/7.348 V1=12.2 V.

Now, for the potential at point P due to the line of charge, we will need to first calculate the linear charge density (λ) of the line of charge.λ=q/l,  Where λ is the linear charge density, q is the total charge on the line and l is the length of the line.  For the line of charge Y=2, Z=2, the total charge is given as;  Q=λlWhere Q is the total charge and l is the length of the line.  Since the line is infinite, we cannot use the length of the line, we will use the length of the portion of the line from (0,2,2) to (0,-2,2) which is 4 units long.  We can then find the length of the portion of the line from (-∞,2,2) to (0,2,2) which is half of the entire line. Using the Pythagoras theorem, the length of this portion is given by;

√[4^2+(2−2)^2+(2−2)^2] = √16 = 4m.  Then the linear charge density is;

λ=Q/l = 5×10−9 C/4m = 1.25×10−9 C/m.  The electric potential at point P due to the line of charge can be determined using the equation below; V2=λ/2πε0.  ln(b/a) Where V2 is the electric potential, λ is the linear charge density, ε0 is the permittivity of free space, b is the distance between point P and the end of the line of charge and a is the distance between point P and the other end of the line of charge. To calculate V2, we will need to find b and a. The distance between point P and the end of the line of charge is given as;

√[(0−4)^2+(2−5)^2+(2−6)^2] = √45 = 6.708m.  

The distance between point P and the other end of the line of charge is given as;

√[(0−4)^2+(−2−5)^2+(2−6)^2] = √74 = 8.602m.  

So, V2 is; V2=1.25×10−9/2π×9×10^9  ln(8.602/6.708) V2=0.004 V

The total electric potential at point P is the sum of the electric potential due to the point charge and that due to the line of charge.

Thus; VT=V1+V2 = 12.2+0.004 = 12.204 V

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Answer:

The answer is Continental Grip