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icang [17]
3 years ago
9

An object is 45 m above the ground when it is dropped. How fast is the object going just before it hits the ground?

Physics
1 answer:
leonid [27]3 years ago
3 0
This is a kinematics question.
v^{2} = v_{0} ^{2} + 2g(y - y_{0}) \\ 
v^{2} = 0 + 2(-9.8)(0 - 45) \\ 
v^{2} = 882 \\ v =  \sqrt{882}  = 29.7 m/s

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The answer is Monocline. And I checked it, it's correct.

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A ray of light crosses a boundary between two transparent materials. The medium the ray enters has a larger optical density. Whi
Tpy6a [65]

Answer:

The wavelength of the light decreases as it enters into the medium with the greater optical density.

The frequency of the light remains constant as it transitions between materials.

Explanation:

- When a ray of light crosses a boundary between two different materials, it undergoes refraction: the ray changes direction, and it also changes speed, according to the relationship:

v=\frac{c}{n}

where v is the speed of the ray of light in the material, c is the speed of light in a vacuum, n is the index of refraction of the material, which is larger for a medium with larger optical density. So, from the equation, we see that the larger the optical density, the smaller the speed of the wave.

- The frequency of the light does not depend on the properties of the medium, so it remains unchanged: therefore the statement

The frequency of the light remains constant as it transitions between materials.

is correct.

- Moreover, the wavelength of the ray of light is related to the speed and the frequency by the equation

\lambda=\frac{v}{f}

where v is the speed and f the frequency. Since we have seen that v decreases and f remains constant, this means that the wavelength decreases as well, so the statement

The wavelength of the light decreases as it enters into the medium with the greater optical density.

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5 0
3 years ago
1.   A car travels along a straight road to the east for 100 meters in 4 seconds, then go the west for 50 meters in 1 second.
Alla [95]

Answer:

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Explanation:

a. Distance is the change in the position of an object.

The distance covered by the car = 100 + 50

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b. Since displacement is a vector quantity,

Displacement of the car = 100 - 50

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c. Time elapsed is the time taken for the motion of the car starting from when its starts to when it stops.

Thus, the time elapsed = 4 + 1

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4 0
3 years ago
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earnstyle [38]

Answer:

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a = (2 - 4)/5 = -2/5 =

a = - 0.4rad/s²

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