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3 years ago

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during a workout, a football player pushes a blocking dummy a distance of 30 m. while pushing the dummy the same distance a seco

nd time, what would the player need to change to be certain that power output increases? the player would need to use a greater force and take more time. the player would need to use a greater force and take less time. the player would need to use a smaller force and take more time. the player would need to use a smaller force and take less time.

2 answers:

babymother [125]3 years ago

8 0

$Power=\frac{Work}{Time}=\frac{Force\times distance}{time}$

If he wants to increase power, force must increase and decrease time.

Dmitrij [34]3 years ago

5 0

B.........................

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Answer:

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And if we make a sum of moments at the point O equal to zero (0).

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A plane travels 350 km south along a straight path with an average velocity of 125 km/h to the south. The plane has a 30 minute

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Average Velocity = Total Displacement / Total time

1st part of journey, 350 km at velocity 125 km/h

Time = 350 / 125 = 2.8 hours.

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Average Velocity = Total Displacement / Total time

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Option C.

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A small airplane takes on 302 l of fuel. If the density of the fuel is 0.821 g/ml, what mass of fuel has the airplane taken on?

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Thus, the mass of the fuel 247 .94 kg.

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3 years ago

The wavelength of red helium-neon laser light in air is 632.8 nm.(a) What is its frequency? Hz(b) What is its wavelength in glas

vekshin1

<h2>Answers:</h2>

The speed of a wave is given by:

$v=f.\lambda$ (1)

Where $f$ is the frequency and $\lambda$ the wavelength.

In the case of light, its speed is:

$c=f.\lambda$ (2)

On the other hand, the described situation is known as Refraction, a phenomenon in which the light changes its direction when passing through a medium with a refractive index different from the other medium.

In this context, the Refractive index $n$ is a number that describes how fast light propagates through a medium or material, and is defined as the relation between the speed of light in vacuum ( $c=3(10)^{8}m/s$ ) and the speed of light $v$ in the second medium:

$n=\frac{c}{v}$ (3)

In addition, as the light changes its direction, its wavelength changes as well:

$n=\frac{\lambda_{air}}{\lambda_{glass}}$ (4)

Knowing this, let's begin with the answers:

<h2>a) Frequency</h2>

From equation (2) we can find $f$ :

$f=\frac{c}{\lambda}$ (5)

Knowing that $1nm=(10)^{-9}m$ :

$f=\frac{3(10)^{8}m/s}{632.8(10)^{-9}m}$

$f=4.74(10)^{14}Hz}$ (6) >>>Frequency of the helium-neon laser light

<h2>b) Wavelength in glass</h2>

We already know the wavelength of the light in air $\lambda_{air}$ and the index of refraction of the glass.

So, we only have to find the wavelength in glass $\lambda_{glass}$ from equation (4):

$\lambda_{glass}=\frac{\lambda_{air}}{n}$

$\lambda_{glass}=\frac{632.8(10)^{-9}m}{1.48}$

$\lambda_{glass}=427(10)^{-9}m=427nm$ (7) >>>Wavelength of the helium-neon laser light in glass

<h2>c) Speed in glass</h2>

From equation (3) we can find the speed $v$ of this light in glass:

$v=\frac{c}{n}$

$v=\frac{3(10)^{8}m/s}{1.48}$

$v=2.027(10)^{8}m/s$ (8) >>>Speed of the helium-neon laser light in glass

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3 years ago