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Alex
3 years ago
12

How was helium first discovered?

Physics
2 answers:
Olenka [21]3 years ago
7 0

Answer:

using spectral analysis of the Suns’ emission spectra

Explanation:

lora16 [44]3 years ago
3 0
I think it’s the third one idk tho
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Directions: Select the choice that best fits each statement. The following question(s) refer to the following concepts related t
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(E) Second law of thermodynamics

Explanation:

The second law of thermodynamics can be understood according to Clausius' words: In an isolated system, no process can occur if a decrease in the total entropy of the system is associated with it. These processes are associated with energy transformations, in which a variable is introduced, called entropy that indicates the notion of disorder. Therefore, in any isolated process, the disorder can only grow.

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3 years ago
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If sodium has one valence electron and sulfur has six, how many sodium atoms are needed to form an ionic bond with sulfur?
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a cart has 30J or potential energy at the top of a 20m high hill. Assuming no energy is transformed to another form of energy, h
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i would say 20J

Explanation:

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3 years ago
A stone that is dropped freely from rest traveled half the total height in the last second. with what velocity will it strike th
alexira [117]

Answer:

hellooooo :) ur ans is 33.5 m/s

At time t, the displacement is h/2:

Δy = v₀ t + ½ at²

h/2 = 0 + ½ gt²

h = gt²

At time t+1, the displacement is h.

Δy = v₀ t + ½ at²

h = 0 + ½ g (t + 1)²

h = ½ g (t + 1)²

Set equal and solve for t:

gt² = ½ g (t + 1)²

2t² = (t + 1)²

2t² = t² + 2t + 1

t² − 2t = 1

t² − 2t + 1 = 2

(t − 1)² = 2

t − 1 = ±√2

t = 1 ± √2

Since t > 0, t = 1 + √2.  So t+1 = 2 + √2.

At that time, the speed is:

v = at + v₀

v = g (2 + √2) + 0

v = g (2 + √2)

If g = 9.8 m/s², v = 33.5 m/s.

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3 years ago
According to the Hooke’s law formula, the force is proportional to what measurement?
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According to Hooke's Law formula. The force is proportional to the displacement of the spring. I believe
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