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2 years ago

15

O desenho de uma estrela com uma data em baixo, que se vê no lado esquerdo do anúncio, constitui um código muito conhecido em no

ssa sociedade

2 answers:

Fed [463]2 years ago

7 0

Yeah.. that’s hard.....

Yuri [45]2 years ago

7 0

The drawing of a star with a date below, seen on the left side of the ad, is a well-known code in our society

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Which of the following is a typical property of an iconic compound

tino4ka555 [31]

High boiling and melting points

6 0

3 years ago

Read 2 more answers

while hunting in a cave a bat emits sounds wave of frequency 39 kilo hartz were moving towards a wall with a constant velocity o

MariettaO [177]

Complete question:

while hunting in a cave a bat emits sounds wave of frequency 39 kilo hartz were moving towards a wall with a constant velocity of 8.32 meters per second take the speed of sound as 340 meters per second. calculate the frequency reflected off the wall to the bat?

Answer:

The frequency reflected by the stationary wall to the bat is 41 kHz

Explanation:

Given;

frequency emitted by the bat, = 39 kHz

velocity of the bat, $v_b$ = 8.32 m/s

speed of sound in air, v = 340 m/s

The apparent frequency of sound striking the wall is calculated as;

$f' = f(\frac{v}{v- v_b} )\\\\f' = 39,000(\frac{340}{340 -8.32} )\\\\f' = 39978.29 \ Hz$

The frequency reflected by the stationary wall to the bat is calculated as;

$f_s = f'(\frac{v + v_b}{v} )\\\\f_s = 39978.29(\frac{340 + 8.32}{340} )\\\\f_s = 40,956.56 \ Hz$

$f_s\approx 41 \ kHz$

3 0

3 years ago

Given the frequency of an electromagnetic wave, what else can you find immediately?

Oksana_A [137]

Answer:

wavelength

Explanation:

An electromagnetic waves is produced due to interaction of oscillating electric and magnetic field when they interacts perpendicular to each other. For example, Gamma rays, X rays , ultraviolet rays, visible radiations, infrared rays, micro waves, radio waves.

All the electromagnetic waves have velocity equal to velocity of light.

If the frequency of electromagnetic wave is unknown then we find the wavelength of wave. the formula used is

Wave speed = wavelength x frequency

3 0

3 years ago

What, roughly, is the percent uncertainty in the volume of a spherical beach ball whose radius is 5.66 0.09 m?

iren2701 [21]

Answer:

4.77 %

Explanation:

We know that the volume V for a sphere of radius r is

$V(r) = \frac{4}{3} \ \pi \ r^3$

If we got an uncertainty $\Delta r$ the formula for the uncertainty of V is:

$\Delta V(r) = \sqrt{ (\frac{dV}{dr} \Delta r)^2 }$

We can calculate this uncertainty, first we obtain the derivative:

$\frac{dV}{dr} = 3 * \frac{4}{3} \ \pi \ r^2$

$\frac{dV}{dr} = 4 \ \pi \ r^2$

And using it in the formula:

$\Delta V(r) = \sqrt{ (4 \ \pi \ r^2\Delta r)^2 }$

$\Delta V(r) = \sqrt{ 4^2 \ \pi^2 \ r^4 \Delta r^2 }$

$\Delta V(r) = 4 \ \pi \ r^2 \Delta r$

The relative uncertainty is:

$\frac{\Delta V(r)}{V(r)}$

$\frac{ 4 \ \pi \ r^2 \Delta r }{ \frac{4}{3} \ \pi \ r^3}$

$\frac{ 3 \Delta r }{ r}$

Using the values for the problem:

$\frac{ 3 * 0.09 m }{ 5.66 m} = 0.0477$

This is, a percent uncertainty of 4.77 %

4 0

2 years ago

The perceived loudness of a sound is measured in

diamong [38]

<h2>Answer: decibels </h2>

The decibel $dB$ is the relation between two values: the pressure produced by a sound wave and a pressure taken as a reference. Resulting in a dimensionless value.

It should be noted that itself<u> is not a unit of measure</u>, since in reality the unit is bel $B$ (which <u>is not part of the International System of Units</u>) in honor of Alexander Graham Bell.

However, given the amplitude of the measured elements in practice, its submultiple, the decibel, is used. That is, this quotient is a logarithmic expression, where $1dB=0.1B$

5 0

2 years ago