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3 years ago

What stays constant in a reaction?

1 answer:

3 0

Correct answers is D.

Explanation:
Reaction most often happens between two chemicals. But it can also happen with only one chemical. Heating of water is also a reaction.

When we heat the water we bring thermal energy to it. This causes raise of temperature and water starts boiling. This creates water vapour. In this way the amount of water in liquid and gas states changes. This eliminates answers B and C.

Freezing of water is also a reaction. When the water freezes it increases it's volume. This eliminates answer A.

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a 42.3 kg girl and a 7.93 kg sled are on the surface of a frozen lake, 15.0m apart and linked by a rope, but not moving yet. the

ycow [4]

Answer:

they meet from the girl's original position at: 2.37 (meters)

Explanation:

We need to use the Newton's law, exactly the second law that relate force, mass and acceleration as: $F=m*a$ with this we can get both accelerations; solving for acceleration $a=\frac{F}{m}$ . Now $a_{girl}=\frac{5.76}{42.3}=0.14 (m/s^{2})$ and $a_{sled}=\frac{5.76}{7.93}=0.73(m/s^{2})$ . Then knowing that they both travel at the same time and assuming that the distance among the girl and the sled is: 15.0-x, so, $x=\frac{1}{2}*a_{girl}*t^{2}$ and $15.0-x=\frac{1}{2}*a_{sled}*t^{2}$ , solving for the time we get: $t=\sqrt{\frac{2x}{a_{girl} } }$ and $t=\sqrt{\frac{2*(15.0-x)}{a_{sled} } }$ with this equations we solving for the x that is the distance between the girl and the sled after the apply the force and we get: $\sqrt{\frac{2x}{a_{girl}}} = \sqrt{\frac{2*(15.0-x)}{a_{sled} }$ . Finally we get: $\frac{x}{a_{girl} }=\frac{(15.0-x)}{a_{sled} }$ and replacing the values we have got: $\frac{x}{0.14} =\frac{(15.0-x)}{0.73}$ so $5.33*x=15-x$ so x=2.37 (meters).

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3 years ago

Seven seconds after a brilliant flash of lightning, thunder shakes the house. How far was the lightning strike from the house? S

Zepler [3.9K]

Answer:

About two kilometers away

$\rm distance=2.401\ km$

Explanation:

Given:

The time gap between the light and sound to travel to the house, $t=7\ s$

<em>Since the clouds are formed in the troposphere region of the atmosphere which extends from 8 kilometers to 12 kilometers above the earth-surface and the velocity of light is 300000 kilometers per second so it is visible almost instantly, hence we neglect the time taken by the light to travel to the house from the clouds.</em>

<u>∴Distance between the lightning-strike and the house:</u>

$\rm distance=v\times t$

we have the speed of sound as: $v=343\ m.s^{-1}$

So,

$\rm distance=343\times 7$

$\rm distance=2401\ m$

$\rm distance=2.401\ km$

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3 years ago

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There are 6 types of quarks.

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<h2>Answer</h2>

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<h2>Explanation</h2>

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