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Arlecino [84]
3 years ago
7

Sand is made of tiny pieces of rock that have been worn down by wind and water. Explain why the formation of sand is a physical

change.
Physics
2 answers:
Sliva [168]3 years ago
8 0

The formation of sand is a physical change because some of the physical properties of the rocks change, but their identities do not. The particles of rock are rearranged as their sizes and shapes change, but their identities and total mass remain the same.

katovenus [111]3 years ago
8 0

The formation of sand is a physical change because some of the physical properties of the rocks change, but their identities do not. The particles of rock are rearranged as their sizes and shapes change, but their identities and total mass remain the same.



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A man stands still on a moving walkway that is going at a speed of 0.2 m/s to
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Answer:

0.2 m/s east

Explanation:

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3 years ago
How much time does it take a dropped object to fall 180 m on Earth?
rusak2 [61]

Answer:

6s

Explanation:

Assume it is dropped from rest and the gravitational acceleration is 10

By the equation of motion under constant acceleration:

s=ut+\frac{1}{2} at^2

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3 years ago
7.22 Ignoring reflection at the air–water boundary, if the amplitude of a 1 GHz incident wave in air is 20 V/m at the water surf
Serga [27]

Answer:

z = 0.8 (approx)

Explanation:

given,

Amplitude of 1 GHz incident wave in air = 20 V/m

Water has,

μr = 1

at 1 GHz, r = 80 and σ = 1 S/m.

depth of water when amplitude is down to  1 μV/m

Intrinsic impedance of air = 120 π  Ω

Intrinsic impedance of  water = \dfrac{120\pi}{\epsilon_r}

Using equation to solve the problem

  E(z) = E_0 e^{-\alpha\ z}

E(z) is the amplitude under water at z depth

E_o is the amplitude of wave on the surface of water

z is the depth under water

\alpha = \dfrac{\sigma}{2}\sqrt{\dfrac{(120\pi)^2}{\Epsilon_r}}

\alpha = \dfrac{1}{2}\sqrt{\dfrac{(120\pi)^2}{80}}

\alpha =21.07\ Np/m

now ,

  1 \times 10^{-6} = 20 e^{-21.07\times z}

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taking ln both side

21.07 x z = 16.81

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5 0
4 years ago
1.)A tank travels at a rate of 10.0 km/hr for 12.00 minutes, then at 15.0 km/hr for 8.00
rosijanka [135]

12.00 min = 0.2 hr

8.00 min = 0.15 hr

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= 8.25 km

Average speed:

(10.0 km/hr + 15.0 km/hr + 20.0 km/hr) / 3

= 15 km/hr

Change in position:

(10.0 km/hr) (0.2 hr) + (15.0 km/hr) (0.15 hr) - (20.0 km/hr) (0.2 hr)

= 0.25 km

Average velocity:

(10.0 km/hr + 15.0 km/hr - 20.0 km/hr) / 3

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3 years ago
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goblinko [34]
It's Photoelectric Effect, I just a test with this same question. I am not good for explaining exactly how, but I was right.
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