A stationary siren on a firehouse is blaring at 81Hz. Assume the speed of sound to be 343m/s. What is the frequency perceived by a firefighter racing toward the station at 11km/h

[tex] \text{u =?} \\ \text{ v = 24cm} \\ \text{ m = 0.5} \\ \text{ f = ?}[/tex]

[tex] \implies \text{m} = \frac{ \text{v}}{ \text{u}} = \frac{24}{ \text{u}} [/tex]

[tex] \implies 0.5 = \frac{1}{2} = \frac{24}{ \text{u}} \\ \\ \therefore \text{u} = 48 \text{cm}[/tex]

[tex] \implies \frac{1}{ \text{f}} = \frac{1}{ \text{v}} - \frac{1}{ \text{u}} [/tex]

[tex] \implies \text{f} = \frac{1}{24} - \frac{1}{48} = \frac{2 - 1}{48} = \frac{1}{48} [/tex]

[tex] \text{f} = 48 \text{cm}[/tex]

[tex]\underline{ \text {According To Question,}}[/tex]

[tex] \text{24cm is the distance of object from lens,}[/tex]

[tex] \text{m} = \frac{ \text{v}}{ \text{u}} \\ \\ \implies \frac{1}{2} = \frac{ \text{u}}{24} [/tex]

[tex] \therefore \text{v} = \frac{24}{2} = 12 \text{cm}[/tex]

[tex] \implies \frac{1}{ \text{f}} = \frac{1}{ \text{v}} - \frac{1}{ \text{u}} [/tex]

[tex] \implies \frac{1}{ \text{f}} = \frac{1}{12} - ( \frac{1}{ - 24} )[/tex]

[tex] \implies \frac{1}{ \text{f}} = \frac{1}{12} + \frac{1}{24} = \frac{2 + 1}{24} = \frac{3}{24} [/tex]

[tex] \implies \text{f} = \frac{24}{3} = 8 \text{cm}[/tex]

Answer: (A) The number of waves that pass a point in a certain amount of time.  

Explanation:

Electromagnetic waves are categorized according to their frequency f or, equivalently, according to their wavelength λ = c/f. Visible light has a wavelength range from ~400 nm to ~700 nm.

Frequency: Is the number of waves that pass a certain point in a specified amount of time.

Trough: The low point of the wave cycle.

Wavelength: The distance between two successive peaks.

Electromagnetic wave: One of the waves that are propagated by simultaneous periodic variations of electric and magnetic field intensity.

Answer:

C. Stimulus = temperature, response = sweat

Explanation:

So basically, stimulus means cause and response means effect.

So, the cause in this case is temperature, while the response to the temperature is sweating.

The change in frequency noticed by observers on sub b is : 2.66 Hz before the submarines pass each other.

Given data:

New speed of Sub b ( Vb ) = 12.4 m/s

F₁ = 1416.44 Hz

Frequency of sonar wave ( Fₐ ) = 1400 Hz

Speed of sound in water ( V ) = 1533 m/s

Speed of submarine A ( Va ) = 8.4 m/s

The change in frequency can be calculated using the formula below

F₁' = Fₐ ( V + Vb / V - Vₐ )

    = 1400 ( 1533 + 12.4 / 1533 - 8.4 )

    = 1400 ( 1545.4 / 1524.6 )

    = 1419.1 Hz

Final step : determine the change in frequency

ΔF = F₁' - F₁

    = 1419.1 - 1416.44

    = 2.66 Hz.

Hence we can conclude that The change in frequency noticed by observers on sub b is : 2.66 Hz.

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The frequency is the number of waves that travel through a particular place in one unit of time. The change in frequency noticed by observers on sub b is 2.66 Hz.

The frequency is the number of waves that travel through a particular place in one unit of time. It may also be described as the number of cycles or vibrations experienced by a body in periodic motion in one unit of time.

Given that the new speed of the sub B is 12.4 m//sec, while the frequency of the submarine is 1416.44 Hz. The frequency of the sonar wave of submarine A is 1400 Hz. Also, the speed of sound in water, V is 1533 m/sec, and the speed of submarine A is 8.4 m/s.

Now, the frequency of the sub B after the speed is increased will be equal to,

[tex]F_1' = F_a \times \dfrac{(V+V_b)}{(V-V_a)}[/tex]

      [tex]\rm = 1400 \times \dfrac{(1533+12.4)}{(1533-8.4)}\\\\=1400 \times \dfrac{1545.4}{1524.6}\\\\=1419.1\ Hz[/tex]

Further, the change in frequency noticed by observers on sub b,

[tex]\rm \triangle F = F_1'-F_1 = 1419.1-1416.44 = 2.66\ Hz[/tex]

Hence, the change in frequency noticed by observers on sub b is 2.66 Hz.

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An expression for the coefficient of kinetic friction between the block and the horizontal surface is given as μk = Ff/mg.

The coefficient of kinetic friction is the force of frcition between a moving object and the horizontal surface.

The expression for the coefficient of kinetic friction between the block and the horizontal surface is given as;

Ff = μkFₙ

Ff = μkmg

μk = Ff/mg

where;

Thus, an expression for the coefficient of kinetic friction between the block and the horizontal surface is given as μk = Ff/mg.

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The statement the power of an electric heater is 1200 W means that the electric heater used up 1200 J of electric energy in one second.

When the velocity of a moving body is doubled, its kinetic energy will become four times its initial kinetic energy.

Power is the rate at which energy is used up. The s.i unit of power is Watt (W).

From the question, if an electric heater is 1200 W, it means that the electric heater used up 1200 J of electric energy in one second

Kinetic energy is the energy of a body in motion.

The formula for the kinetic energy of a body is given as

From the equation above, it can be seen that if the velocity of a moving body is doubled, the kinetic energy of the body will become four times the initial kinetic energy of the body.

Hence, The statement the power of an electric heater is 1200 W means that the electric heater used up 1200 J of electric energy in one second.

When the velocity of a moving body is doubled, its kinetic energy will become four times its initial kinetic energy.

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Answer:

C. In a valley .

.............................

Answer:

Sources of greenhouse gases

Natural sources include respiration and decomposition of plants and ocean release of greenhouse gases to the atmosphere. Many natural GHGs occur naturally in the atmosphere, such as water vapour, carbon dioxide, methane and nitrous oxide. Some greenhouse gases are synthetic, human-made.

Answer:

No the butterflies wings won't glow.

Explanation:

Butterflies have wings that have different color of attractiveness. Butterflies are however attracted to light but can't absorb the light.

Answer:

the reaserch I did says that d is the correct answer

Answer:

Repulsion

Explanation:

Unlike attraction of magnets opposite polls

Answer:

Repulsion

Explanation:

Brainliest MisterBrainly

[tex]\red{ \rule{0pt}{900000pt}}[/tex]

Answer:

Dipole

Explanation:

A pair of opposite electric charges of equal magnitude is called a(n)

Answer:

Dipole

Explanation:

Explanation:

How are animals similar? All animals are made of many cells. Most animals can move on their own. Like all living things, animals grow, change, reproduce, and respond to their environment.

Answer:

D

Explanation:

The digestive system does all of these functions

all these components (and more) make up the digestive system.

if you are unsure, visit bbc bitesize for more information.

The parts found in an electric generator for the conversion of electric energy into other forms of energy such as mechanical or chemical energy are an armature, a permanent magnet, an electromagnet brushes, and slip rings.

An electric generator is a device that converts motive power into electric power for use in an external circuit.

Parts of electric generators include the following;

These parts of electric generator helps in the generation of electricity or conversion of electric energy into mechanical energy or light energy or chemical energy.

Thus, the parts found in an electric generator for the conversion of electric energy into other forms of energy such as mechanical or chemical energy are an armature, a permanent magnet, an electromagnet brushes, and slip rings.

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Answer:

armature

permanent magnet

electromagnet

brushes

slip rings

Explanation:

edge 2022-2023

if the primary winding has 50 coils and the secondary winding has 20 coils then the secondary  voltage will be equal to 2400V

Voltage is defined as the potential difference which apply a force on the charge to flow in the circuit.

This is a question on transformer. A transformer is a device used to step up or step down current and voltage. It consists of the primary windings and secondary windings. Each windings possesses both coil and amount of voltage across each coil.

The transformer formula is

[tex]\dfrac{V_S}{V_P}=\dfrac{N_S}{N_P}[/tex]

Where;

Vs is the voltage across the secondary coil

Vp is the voltage across the primary coil

Ns is the number of turn in the primary coil

Np is the number of turns in the primary coil.

According to the question,

Vs is unknown

Vp is 6000V

Ns is 20turns

Np is 50turns

Substituting the values in the formula given

[tex]\dfrac{V_S}{6000}=\dfrac{20}{50}[/tex]

Vs = 2400V

Therefore the secondary voltage is 2400V

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Answer:

2400

Explanation:

edge 2022

Answer:

2:1

Explanation:

Answer:

When waves overlap in-phase (crest meets crest or trough meets trough) the waves energy is additive and the amplitude increases.

Explanation:

When waves overlap out-of-phase (crest meets trough) the waves cancel and the amplitude (energy) decreases. When two interfering waves cancel each other out.

Answer:

12*10^(-6) or 1.2*10^(-5)

Explanation:

if both of spheres are in same size.

q after = (q1+q2)/2 = ( (4.0 + 20.0)*10^(-6) )/2 = 12*10^(-6) or 1.2*10^(-5)

The net torque on the seesaw is 294 Nm.

Torque is the force that tends to rotate the body to which it was applied.

To calculate the net torque, we use the formula below

Formula:

Where:

From the question,

Given:

Substitute these values into equation 1

Hence, The net torque on the seesaw is 294 Nm.

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Answer:

They're are Conditions .... (L00K D0WN.)

Explanation:

Conditions for equilibrium require that the sum of all external forces acting on the body is zero (first condition of equilibrium), and the sum of all external torques from external forces is zero (second condition of equilibrium). These two conditions must be simultaneously satisfied in equilibrium.

Answer: See below

Explanation:

[tex]\\ \mathrm{Given:} \\\mathrm{Mass \ of \ first \ car}$\left(m_{1}\right)=1383 \mathrm{~kg}$ \\ Velocity $\left(\overrightarrow{V_{1}}\right)=-11.2\ {\math} \mathrm{m} / \mathrm{s}$\\ Mass of second car -$\left(m_{2}\right)=1732 \mathrm{~kg}$\\ Velocity $\left(\vec{v}_{2}\right)=31.3 {\math} \mathrm{m} / \mathrm{s}$[/tex]

[tex]m_{1} \vec{v}_{1}+m_{2} \vec{v}_{2}=\left(m_{1}+m_{2}\right) \vec{v} \\1383(-11.2 {\math})+1732(31.3 {\math}) \\=(1383+1732) \vec{v} \\-15489.6 {\math}+54211.6 {\math}=3115 \vec{v} \\ \vec{v}=(17.4 {\math}-4.972 {\math}) \ \mathrm{m/s}[/tex]

[tex]\text { So magnitude } \vec{|v|} =\sqrt{(17.4)^{2}+(-4.972)^{2}} \\ =\sqrt{327.605} \\ =18.099 \mathrm \ {m/s} \\[/tex]

[tex]\text { Direction } \\\theta=\tan ^{-1}\left(\frac{-4.972}{17.4}\right) \\\theta=-15.945^{\circ}\end{gathered}[/tex]

Therefore, both cars move with a velocity of 18.099 m/s in the direction of 15.945° downward from the x-axis (east)

Answer:

Explanation:

Apply conservation of momentum in N-S direction:

Initial momentum: 1383*(-11.2) + 1732*(0) = -15490

Final momentum: (1383 + 1732) * Final N-S velocity = -15490

Final velocity = 1549/(1383+1732) = -4.97 m/s (-ve means South)

Repeat the same for E-W direction:

Initial momentum: 1383*(0) + 1732*(31.3) = 54211.6

Final momentum: (1383 + 1732) * Final E-W velocity = 54211.6

Final velocity = 54211.6/(1383+1732) = 17.4 m/s (+ve means East)

Combining, the final velocity = sqrt (-4.97^2 + 17.4^2) = 18.10 m/s

at direction of arctan(17.4/4.97) = 74 degree South of East.

Answer:

A

Explanation:

The endocrine system has all of the body's hormones it regulates the biological processes. For example it can help brain development, nervous system development, and it can regulate blood sugar. (This is the closest to A)

Answer:

Lunar eclipses are more widely visible because Earth casts a much larger shadow on the Moon during a lunar eclipse than the Moon casts on Earth during a solar eclipse.

Answer:

E = 1/2 K x^2        (1/2 *F * x * x)

E = 2300 / 2 N/m * (.18 m)^2 = 37.3 Joules

The quantity of elastic potential energy that is currently stored in the system is equal to 37.26 Joules (J).

We may use the formula for elastic potential energy to compute the amount of elastic potential energy that is stored in the system, which is as follows:

PE, or Elastic Potential Energy, is 0.5 times k times x squared.

where k represents the constant force that the spring exerts and x represents the amount of compression that the spring experiences.

Given:

The spring has a force constant of 2300 Newton-meters (k).

The spring was compressed (x) by 18.0 centimetres, which is equivalent to 0.18 metres when measured in metres.

To finish, enter the values into the formula as follows:

PE = 0.5 × 2300 N/m × (0.18 m)² PE = 0.5 × 2300 N/m × 0.0324 m² PE = 37.26 J

37.26 Joules (J) is the amount of elastic potential energy that is stored in the system.

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Answer:

The answer is B

Explanation:

This is the only statement that is opinionated, therefore it is the only claim.

Answer: A wave model is most useful for describing the frequency of the radiation

Explanation:

I just took the test

Answer: 80 coils

Explanation for 80 coils: voltage across the secondary winding is 10,000 V, and the voltage across the primary winding is 25,000 V. If the primary winding has 200 coils, how many coils are in the secondary winding...The voltage across the primary winding is 6000 V!