The correct answer is D. I alread took this test.
Answer:
It is an SI unit
Explanation:
The metre is defined as the length of the path travelled by light in a vacuum in 1299 792 458 of a second. The metre was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole
Answer:
This was my best estimation of the answers
B. Helium because it is constantly being made in the sun
Explanation:
From the given paragraph, we can conclude that helium is the most common element in a star such as the sun because it is constantly being made.
In the nuclear fusion process that results in the production of helium, hydrogen nuclei are the reactants and helium is the product.
- since the reactants are constantly being used in the core of the sun, this suggests that the products must be more.
- The reaction requires a high temperature and pressure to initiate.
- It is a series of chain reaction that uses a fuel of hydrogen to produce helium.
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Answer:
The speed of water must be expelled at 6.06 m/s
Explanation:
Neglecting any drag effects of the surrounding water we can assume the linear momentum in this case is conserves, that is, the total initial momentum of the octopus and the water kept in it cavity should be equal to the total final linear momentum. That's known as conservation of momentum, mathematically expressed as:

with Pi the total initial momentum and Pf the final total momentum. The total momentum is the sum of the momentums of the individual objects, in our case the octopus and the mass of water that will be expelled:

with Po the momentum of the octopus and Pw the momentum of expelled water. Linear momentum is defined as mass times velocity:

Note that initially the octopus has the water in its cavity and both are at rest before it sees the predator so
:

We should find the final velocity of water if the final velocity of the octopus is 2.70 m/s, solving for
:


The minus sign indicates the velocity of the water is opposite the velocity of the octopus.