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3 years ago

Which option is an element?

2 answers:

7 0

The correct answer is carbon and the only element listed. Carbon Dioxide is made up of Carbon and Oxygen x2. This would be a compound. Air is made of water and another mixture of Hydrogen x2 and Oxygen.

Hope this helped! :))

Marta_Voda [28]3 years ago

3 0

Carbon is an element so answer choice B.

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3 years ago

Read 2 more answers

The amount of the lighted side of the moon you can see is the same during

attashe74 [19]

Answer:

The amount of the lighted side of the moon you can see is the same during "how much of the sunlit side of the moon faces Earth".

Explanation:

The Moon is in sequential rotation with Earth, and thus displays the Sun, the close side, always on the same side. Thanks to libration, Earth can display slightly greater than half (nearly 59 per cent) of the entire lunar surface.

The side of the Moon facing Earth is considered the near side, and the far side is called the reverse. The far side is often referred to as the "dark side" inaccurately but it is actually highlighted as often as the near side: once every 29.5 Earth days. During the New Moon the near side becomes blurred.

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3 years ago

A 50.0 Watt stereo emits sound waves isotropically at a wavelength of 0.700 meters. This stereo is stationary, but a person in a

photoshop1234 [79]

Answer:

a) f' = 432 Hz

b) I = 8.12*10^-4 W/m^2

Explanation:

a) To calculate the frequency of sound waves that car receives, you take into account the Doppler effect. In this case (observer moves away of the source) you have the following formula:

$f'=f(\frac{v-v_o}{v+v_s})$ (1)

where

f: frequency of the source = ?

v: speed of sound = 343 m/s

vo: speed of the observer = 40.0 m/s

vs: speed of the source = 0 m/s (stationary)

You replace the values of all parameters in the equation (1):

To calculate f' you first calculate the frequency of the sound wave, by using the following formula:

$v=\lambda f\\\\$

v: speed of sound

λ: wavelength = 0.700 m

$f=\frac{v}{\lambda}=\frac{343m/s}{0.700m}=480Hz$

Next, you replace the values of all parameters in the equation (1):

$f'=(490Hz)(\frac{343m/s-40.0m/s}{343m/s})=432Hz$

hence, the frequency perceived by the car is 432 Hz

b) To calculate the power of the sound wave, when the car is 70.0 maway from the speaker, you use the following formula:

$I=\frac{P}{4\pi r^2}$

P: power of the source = 50.0 W

r: distance to the source = 70.0 m

$I=\frac{50.0 W}{4\pi(70.0m)^2}=8.12*10^{-4}\frac{W}{m^2}$

hence, the intensity is 8.12*10^⁻4 W/m^2

3 0

3 years ago

Evaluate A car company wants to build a wind-powered car that converts 100 percent of the mechanical energy in the wind to the m

lorasvet [3.4K]

Answer:

There's one or two reasons, depending on what is meant by "wind-powered car".

The first reason is that it's impossible for any transfer of energy to be 100% efficient. There will always be frictional losses.

Secondly, if the company means that they want to attach a wind turbine to the car so that the car is powered by the same wind that it generates, that violates the conservation of energy.

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4 years ago