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STALIN [3.7K]
3 years ago
10

Which object is most efficient?

Physics
1 answer:
Radda [10]3 years ago
7 0

Answer:

It is b

Explanation:

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A rocket moves upward, starting from rest with an acceleration of 29.4 m/s^2 for 3.98 s. it runs out of fuel at the end of 3.98
ValentinkaMS [17]
The distance d₁ it rises from rest while the engine is burning is given by
d₁ = d₀ + v₀t + (1/2)at²
d₁ = 0 + 0 + (1/2)·(29.4 m/s²)·(3.98 s)² = 232.85 m
So it gets to 232.85 m and then runs out of fuel.  Its velocity v₁ at this point is given by
v₁ = v₀ + at = (29.4 m/s²)·(3.98 s) = 117 m/s
At this point, gravity begins to slow it down until it reaches its peak where its velocity v₂ is zero.
v₂² = v₁² + 2ad₂
where d₂ is the distance it rises until v=0
Since gravity is decelerating the rocket, a = -g, and we have
0² = (117 m/s)² + 2(-9.8 m/s²)d₂
0 = (117)² - (19.6)·d₂
0 = 13,689 - (19.6)·d₂
d₂ = 13,689/19.6 = 698.42 m
So the total height it rises is given by
d₁ + d₂ = 232.85 m + 698.42 m
= 931.27 m





5 0
4 years ago
What is the concentration of H+ ions at a pH = 8?
skelet666 [1.2K]

Taking into account the definition of pH and pOH, the concentration of H⁺ ions at pH=8 is 1×10⁻⁸ M and the concentration of OH⁻ ions at pH=8 is 1×10⁻⁶ M.

<h3>Definition of pH</h3>

pH is a measure of acidity or alkalinity that indicates the amount of hydrogen ions present in a solution or substance.

The pH is defined as the negative base 10 logarithm of the activity of hydrogen ions, that is, the concentration of hydrogen ions or H₃O⁺:

pH= - log [H⁺]= - log [H₃O⁺]

<h3>Definition of pOH</h3>

Similarly, pOH is a measure of hydroxyl ions in a solution and is expressed as the logarithm of the concentration of OH⁻ ions, with the sign changed:

pOH= - log [OH⁻]

<h3 /><h3>Relationship between pH and pOH</h3>

The following relationship can be established between pH and pOH:

pOH + pH= 14

<h3>Concentration of H⁺ ions</h3>

In this case, pH=8. Replacing in the definition of pH:

8= - log [H⁺]

Solving:

<u><em>[H⁺]= 10⁻⁸= 1×10⁻⁸ M</em></u>

Finally, the concentration of H⁺ ions at pH=8 is 1×10⁻⁸ M.

<h3>Concentration of OH⁻ ions</h3>

Being pH= 8, pOH is calculated as:

pOH + 8= 14

pOH= 14 - 8

pOH= 6

Replacing in the definition of pOH the concentration of OH⁻ ions is obtained:

- log [OH⁻]= 6

Solving

<u><em>[OH⁻]= 10⁻⁶= 1×10⁻⁶ M</em></u>

Finally, the concentration of OH⁻ ions at pH=8 is 1×10⁻⁶ M.

Learn more about pH and pOH:

brainly.com/question/16032912

brainly.com/question/13557815

#SPJ1

7 0
2 years ago
What is the target heart rate for a 24 year old?
andriy [413]

Answer:

196

Explanation:

subtract 24 from 220 to get your answer.

6 0
3 years ago
Read 2 more answers
2. A Formula One race car speeds up from rest to 27.8 m/s in a distance of 25 meters.
Nadya [2.5K]

Answer:

Correct answer:   a = 15.46 m/s²

Explanation:

The formula for accelerated movement with the given data is:

V² - V₀² = 2 · a · d     where the initial velocity  V₀ and the final V  

Since the initial velocity V₀ is zero, the formula is:

V² = 2 · a · d  => a = V² / (2 · d) = 27.8² / (2 · 25) = 772.84 / 50 = 15.46 m/s²

a = 15.46 m/s²

God is with you!!!

4 0
3 years ago
Change in velocity from 2 to -3
Alecsey [184]

Velocity units =m/s

Acceleration is the rate of change of velocity

a =timechange in velocity

Therefore SI units of acceleration is ms−1/s=s2m

5 0
3 years ago
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