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Aleks [24]
3 years ago
5

What causes the change from day to night?

Physics
2 answers:
stepladder [879]3 years ago
7 0
Earths Rotation
Earth's rotation is the rotation of Planet Earth around its own axis. Earth rotates eastward, in prograde motion. As viewed from the north<span> pole star Polaris, Earth turns counter</span>clockwise<span>. </span>
"AB84"
Korolek [52]3 years ago
3 0
The earth rotates as the sun travels around it. If the sun was not was not on the other side, it would be night there, but if the sun was shooting to the side it would be day time.
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A fisherman notices that his boat is moving up and down periodically without any horizontal motion, owing to waves on the surfac
Sedbober [7]

Answer:

v = 1.2 m/s

Explanation:

The wavelength of the waves is given as the horizontal distance between the crests:

λ = wavelength = 5.5 m

Now, the time period is given as the time taken by boat to move from the highest point again to the highest point. So it will be equal to twice the time taken by the boat to travel from highest to the lowest point:

T = Time Period = 2(2.3 s) = 4.6 s

Now, the speed of the wave is given as:

v = f\lambda

where,

v= speed of wave = ?

f = frequency of wave = \frac{1}{T} = \frac{1}{4.6\ s} = 0.217\ Hz

Therefore,

v = (0.217\ Hz)(5.5\ m)\\

<u>v = 1.2 m/s</u>

5 0
2 years ago
An ultrasound unit is being used to measure a patient's heartbeat by combining the emitted 2.0 MHz signal with the sound waves r
alexandr402 [8]
Hi there, 
for this question we have:
Signal 2.0 MHz = Emitted so we can call it f_e
and we need the Reflected = f_{r}
In this question, we have a source which goes to the heart and a reflected which comes back from the heart and we need the speed of the reflected.
So you should know that the speed of reflected is lower than the source(Emitted). 
we also know: ΔBeat frequency(max) = 560 Hz = f_{b}
so we have: 
f_{e} - f_{r} = f_{b}
so frequency of Reflected is: 
2.0 × 10^6 Hz - 560 Hz = 1.99 × 10^6 Hz = f_{r}
now you know that Lambda = v/f 
so if we find the lambda with our Emitted then we can find v with the Reflected: 
Lambda = 1540(m/s) / 2.0 × 10^6 Hz = 7.7 × 10^-4 m 
=> v_{max} = (lambda)(f_{r} 
=> 7.7 × 10^-4m (1.99 × 10^6Hz) = 1532 m/s 
so the v_{max} is equal to 1532 m/s :)))
This question is solved by two top teachers as fast as they could :))
I hope this is helpful
have a nice day

8 0
3 years ago
Which of the following is not a primary cause of eroding rock
Pavel [41]
The answer to this is Animal habitation 
4 0
3 years ago
Freight car A with a gross weight of 200,000 lbs is moving along the horizontal track in a switching yard at 4 mi/hr. Freight ca
zhenek [66]

Answer: a) 4.7 mi/hr.  b) 86,500 lbs. mi²/Hr²

Explanation:

As in any collision, under the assumption that no external forces exist during the very small collision time, momentum must be conserved.

If the collision is fully inelastic, both masses continue coupled each other as a single mass, with a single speed.

So, we can write the following:

p₁ = p₂ ⇒m₁.v₁ + m₂.v₂ = (m₁ + m₂). vf

Replacing by the values, and solving for vf, we get:

vf = (200,000 lbs. 4 mi/hr + 100,000 lbs. 6 mi/hr) / 300,000 lbs = 4.7 mi/hr

If the track is horizontal, this means that thre is no change in gravitational potential energy, so any loss of energy must be kinetic energy.

Before the collision, the total kinetic energy of the system was the following:

K₁ = 1/2 (m₁.v₁² + m₂.v₂²) = 3,400,000 lbs. mi² / hr²

After the collision, total kinetic energy is as follows:

K₂ = 1/2 ((m₁ + m₂) vf²) = 3,313,500 lbs. mi²/hr²

So we have an Energy loss, equal to the difference between initial kinetic energy and final kinetic energy, as follows:

DE = K₁ - K₂ = 86,500 lbs. mi² / hr²

This loss is due to the impact, and is represented by the work done by friction forces (internal) during the impact.

8 0
2 years ago
What description refers to fog?
wolverine [178]
I think the answer is D
4 0
2 years ago
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