just need help with this explain​

Taking into account the definition of wavelength, frecuency and propagation speed, the wavelength for radio waves with a frequency of 100 MHz is 3 m.

First of all, wavelength is the minimum distance between two successive points on the wave that are in the same state of vibration. It is expressed in units of length (m).

On the other side, frequency is the number of vibrations that occur in a unit of time. Its unit is s⁻¹ or hertz (Hz).

Finally, the propagation speed is the speed with which the wave propagates in the medium, that is, it is the magnitude that measures the speed at which the wave disturbance propagates along its displacement.

The propagation speed relate the wavelength (λ) and the frequency (f) inversely proportional using the following equation:

v = f×λ

All electromagnetic waves propagate in a vacuum at a constant speed of 3×10⁸ m/s, the speed of light.

In this case, you know:

Replacing in the definition of propagation speed:

3×10⁸ m/s = 100,000,000 Hz× λ

Solving:

λ= 3×10⁸ m/s ÷ 100,000,000 Hz

λ= 3 m

In summary, the wavelength for radio waves with a frequency of 100 MHz is 3 m.

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Answer:

0.04 °C⁻¹

Explanation:

First, we need to calculate linear expansivity, then after finding that value, we can move on to finding the area expansivity.

=============================================================

Finding Linear Expansivity :

⇒ α = Final length - Original length / (Original length × ΔT)

⇒ α = 9 - 4 / (4 × 70 - 20)

⇒ α = 5 / 5 × 50

⇒ α = 0.02

============================================================

Finding Area Expansivity :

⇒ Area Expansivity = 2 × Linear Expansivity

⇒ β = 2 × α

⇒ β = 2 × 0.02

⇒ β = 0.04 °C⁻¹

Calculate the value of the area expansion of a steel rod of lenght 4cm at 20°c after heating attains another length of 9cm at 70°c.

Area = 0.02

Area Expansity = [tex]0.0 {4}^{ - 1} [/tex]

The force of the person is 90 newtons away from the wall.

Force can be defined as the product of mass and acceleration.

To calculate the force of the person when pushing off the wall, use the formula below.

Formula:

Where:

From the question,

Given:

Substitute these values into equation 1

Hence, the force of the person is 90 newtons away from the wall.

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The two objects perform the same task of measuring time and they are hourglass and sundial.

An hourglass is a device used to measure the passage of time.

The hourglass contains two glass bulbs connected vertically by a narrow neck that allows a regulated flow of a substance from the upper bulb to the lower one.

A sundial is a horological device that is used to measure time of the day when there is sunlight by the apparent position of the Sun in the sky. Unlike hourglass, its doesn't move.

Thus, the two objects perform the same task of measuring time and they are hourglass and sundial.

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The work done to stretch the spring will be 112 J.

The force required to extend or compress a spring by some distance scales linearly with respect to that distance is known as the spring force. Its formula is

F = kx

The given data in the problem is;

F is the spring force =?

K is the spring constant= 8.5 N/m

x is the length by which spring got stretched = 1.2m

The work is done to stretch the spring is;

[tex]\rm W= \frac{1}{2} kx^2 \\\\ W=\frac{1}{2} \times 350 \times (0.850-0.050)^2 \\\\ W=0.5 \times 350 \times (0.80)^2 \\\\W=112 \ J[/tex]

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Answer:

true

Explanation:

Light Years are the longest unit-distance. Our galaxy is numerous light years across.

Decreasing the mass of the car will help increase the acceleration of the car using application of Newton’s laws of motion.

This law discusses the relationship between motion of a substance and the forces acting on it.

Heavy objects are more difficult to move which is why decrease in mass will help increase the acceleration.

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Answer: decreasing the mass of the car

Explanation: this is for a TLDR trust

According to Newton's second Law of motion, if the mass of an object is 10 kg and the force is 10 newtons, then the acceleration is 1m/s².

The acceleration of a moving body can be calculated by dividing the force of the body by its mass.

According to this question, the mass of an object is 10 kg and the force is 10 newtons, then the acceleration can be calculated as follows:

acceleration = 10N ÷ 10kg

acceleration = 1m/s²

Therefore, according to Newton's second Law of motion, if the mass of an object is 10 kg and the force is 10 newtons, then the acceleration is 1m/s².

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The weight of the baseball is 1.47 N.

Weight is the gravitational pool of a body or an object.

To calculate the weight of the body, we use the formula below.

Formula:

Where:

From the question,

Given:

Substitute these values into equation 1

Hence, the weight of the baseball is 1.47 N.

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The average force applied by the ground on the Aeroplane is  16.664 kN.

It states that the force F is directly proportional to the acceleration a of the body and its mass.

F =ma

Given is the mass of aeroplane, m =400 kg and the velocity v = 5000 m/s,

It takes t = 2 min to come to rest, then the acceleration will be

a = velocity /time

a = 5000/(2x60)

a = 41.66 m/s²

According to the Newton's second law of motion.

F = 400 kg x  41.66 m/s²

F = 16.664 kN

Thus, the average force applied by ground on aeroplane is 16.664 kN

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Answer:

0

Explanation:

The displacement is zero since it goes in a full circle and ends up where it started.

Explanation:

accurate quantitative expression, precise predictions and/or rigorous methods of testing hypotheses involving quantifiable predictions and measurements.

Answer:

because it is capable of accurate quantitative expression, meaning they show an absolute precision in their results.

According to the information in the fragment, it can be inferred that it is an example of how scientific development has consequences on pre-established theories and new areas are created in science (option C)

A scientific theory is a term to refer to a set of concepts and observations that are proposed as principles to explain a class of phenomena.

According to the above, the discovery of germs and their relationship with human diseases was an event that changed scientific theories about human diseases because it demonstrated a different explanation than what was believed up to that time.

So, the correct answer is option C because this event changed scientific theory and opened new fields for scientific study and research.

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Answer:

Explanation:

According to the information in the fragment, it can be inferred that it is an example of how scientific development has consequences on pre-established theories and new areas are created in science (option C)

What is a scientific theory?

A scientific theory is a term to refer to a set of concepts and observations that are proposed as principles to explain a class of phenomena.

According to the above, the discovery of germs and their relationship with human diseases was an event that changed scientific theories about human diseases because it demonstrated a different explanation than what was believed up to that time.

So, the correct answer is option C because this event changed scientific theory and opened new fields for scientific study and research.

The air mass would produce cold, dry weather in the winter is continental polar. The correct option is a.

A huge collection of air with evenly uniform degrees of temperature, humidity, and pressure.

Continental air masses which are formed cold and dry. Air mass that forms over northern Canada is known as continental polar air mass. As it moves to South, it brings dry weather like conditions in the United States.

Thus, the correct option is a.

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Based on the calculations, the tension in the string connecting the yo-yo to the boy's finger is equal to: A. 35 Newton.

Given the following data:

Based on the information provided, we can logically deduce that the tension in the string connecting the yo-yo to the boy's finger is equal to the centripetal force acting on it.

Mathematically, centripetal force can be calculated by using this formula:

Fc = mv²/r

Fc = (0.5 × 7²)/0.7

Fc = 24.5/0.7

Fc = 35 Newton.

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Answer:

Then our fires would become massive.

Explanation:

Hope this helps

Answer:

final volume - original volume

Answer:

See below

Explanation:

Place the solid in a graduated cylinder filled with water ( or other non-reactant liquid) and measure the change in volume in the graduated cylinder

Answer:

  c.  1.4×10^5 N

Explanation:

Work is the product of power and time. It is also the product of force and distance. We can equate these two products to find the distance.

__

  Wt = Fd

  (7.0×10^4 N·m/s)(40 s) = F(20 m)

  F = (7.0×10^4)(40/20) N = 1.4×10^5 N

The force exerted by the motor is 1.4×10^5 newtons.

The object D is made up of material Lead. The correct option is D.

The specific heat is the amount of heat required to change the temperature by 1°C. It is denoted by C.

Two 1-kg objects, C and D, increase in temperature by the same amount, but the thermal energy transfer of object C is greater than the thermal energy transfer of object D. The object C has a specific heat of 235 J/kg-K.

Q = m C ΔT

Qc > Qd

The energy transfer is proportional to specific heat.

Specific heat of D must be less. The possible material with specific heat less than the given value is for Lead material.

Thus, the correct option is D.

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Answer:

Explanation:

It apply on how you will protect the egg because you protect the egg at all cost. It's very similar on who is protecting you, You need someone to be there for you always because an egg can't survive on it's own. Just like your life your can't be always rolling around like an egg you need to be safe and always with the person who cares for you. An egg is safe when they are together in a tray just like family and friends.

Answer:

A circuit which has a battery in it will not allow electricity to flow through it. A device called a switch can be used to complete a circuit so that other devices can be switched on or off.

Explanation:

^^^

An equation relating the length that you measure l to the ship's proper length l0  is  

l =l0/y. This is further explained below.

Generally, Any object's length in a moving frame will look shortened or contracted when seen in that direction. The Lorentz transformation may be used to determine the amount of contraction.

In conclusion, To use the Lorentz Lorentz transformation, the length Lo-x2 - may be determined if it is measured in the moving reference frame. Hence the Resultant l = l0/y.

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Since no data table was provided, the wave speed be calculated by taking the mean of speed values.

Also, the mathematically derived speed of sound is 343 m/s at 20 °C.

Sound is an example of a mechanical wave and require a material medium for it's transmission.

The speed of sound in air has been determined to be about 343 m/s at 20 °C.

The average wave speed can be calculated using the formula:

The formula relating speed of a wave, frequency, and wavelength is given below:

It is important to note that in this question, no data table or video was provided.

Therefore, the wave speed be calculated by taking the mean of speed values obtained in the experiment as shown in the video.

Also, the mathematically derived speed of sound is 343 m/s at 20 °C.

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Answer:

40 V

Explanation:

 I will assume that  the resistors are

           100 and 3900 and 1000 OHMS    <=====(NOT W)

In series , the resistances add together 100 + 3900 + 1000 = 5000 ohms total

V = IR

I = V / R      so the total current will be   200 v / 5000 ohms = .04 amps

                   this is the current through all of the resistors

      so for the   1000 ohm resistor     V = IR     .04 (1000) = 40 V

Compass and metal detector are the practical applications of magnetism.

Using a compass to find your way to a campsite and a metal detector to find buried iron objects are the practical applications of magnetism because in these tools magnet is used. Without magnet, they can't perform their function.

So we can conclude that compass and metal detector are the practical applications of magnetism.

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Answer:

1.8kJ

Explanation:

Formula :

Energy used = Power x time

===============================================================

Given :

⇒ Power = 30 W

⇒ Time = 1 minute = 60 seconds

=============================================================

Solving :

⇒ Energy used = 30 W × 60 s

⇒ Energy used = 1,800 J

⇒ Energy used = 1.8kJ

Answer:

1800 joule (1.8kJ)

Explanation:

Formula:

Power = Work / Time

30 = Work / 60

Work = 1800 joule

Work = 1.8kJ

Energy = Work done = 1.8kJ

Hence, Energy used is 1.8kJ.

The total electric field of the rod at a distance, x to the right hand end of the rod is determined as [tex]E = \frac{\lambda}{4\pi \varepsilon _0} [\frac{1}{x} - \frac{1}{x+ l} ][/tex].

An expression for the electric field due to an arbitrary source location at observation location on the x-axis is determined as follows;

E = kq/r²

where;

[tex]\int\limits {dE} \,=\int\limits {\frac{kdQ}{r^2} }\\\\E = \lambda k \int\limits^{x + l}_x {\frac{dr}{r^2}} \,= \lambda k [-\frac{1}{r} ] \\\\E = \lambda k [\frac{1}{x} - \frac{1}{x+ l} ]\\\\E = \frac{\lambda}{4\pi \varepsilon _0} [\frac{1}{x} - \frac{1}{x+ l} ][/tex]

Thus, the total electric field of the rod at a distance, x to the right hand end of the rod is determined as [tex]E = \frac{\lambda}{4\pi \varepsilon _0} [\frac{1}{x} - \frac{1}{x+ l} ][/tex].

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Considering the definition of speed, the speed of Sam is 3.6 [tex]\frac{km}{h}[/tex].

Speed ​​is a quantity that expresses the relationship between the space traveled by an object. That is, the speed is associated with the change of position of an object in space within a certain amount of time.

The speed can be calculated using the expression:

[tex]speed= \frac{displacement}{time}[/tex]

In this case, you know:

Replacing in the definition of speed:

[tex]speed= \frac{9 km}{2.5 h}[/tex]

Solving:

speed= 3.6 [tex]\frac{km}{h}[/tex]

Finally, the speed of Sam is 3.6 [tex]\frac{km}{h}[/tex].

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Answer:

It carries and stores sperm cells that are created in the testes.

The angle that the water surface make with the horizontal is 0.527°.

The water vapor moves at speed. Therefore,

v = 2πr/T = (2 × π × 0.120)/7.25

= 0.104m/s

Also, the top layer of water deals a downward force if gravity which will be:

= mv²/r = 0.104/0.12 = 0.0901

There, the angle will be:

= tan(0.0901/9.8)

= 0.527°

In this case, the angle that the water surface make with the horizontal is 0.527°.

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