There are at least two forces on it, and there could be more.
Vertical forces:
-- gravity, directed downward
-- buoyant force, directed upward
These two forces must be exactly equal, so that the net
vertical force on the raft is zero. Otherwise, it would be
accelerating either up or down.
Horizontal forces:
We know that the net horizontal force on the raft is zero.
Otherwise, it would be accelerating horizontally.
But we don't know if there are actually no horizontal forces
at all, or a balanced group of horizontal forces, that add up
to a net force of zero.
"Changing water salinity" is the most significant challenge for organisms that live in estuaries.
<u>Answer:</u> Option D
<u>Explanation:</u>
For estuaries, alkalinity levels are usually the maximum at a river's mouth where the ocean water falls for, and the minimum upstream where freshwater falls in. Although salinity vary throughout the tidal cycle. In estuaries, salinity rates usually decrease in spring as snow melt and rain raises the freshwater flow from streams and groundwater.
It influences the chemical environments within the estuary, especially the dissolved oxygen (DO) levels in the water. The level of oxygen that would get dissolved in water or its solubility get declined when the alkalinity rises.
First of all, I is proportional V according to the Ohm's Law. R is merely a constant you need to obtain an equation. However, it is true that R changes with temperature and pressure, therefore Ohm's Law is only applicable in an invariable environment. Also this constant R is different for different materials.
So, do not get confused.
Ohm's law is not a universal law, please remember that as well. Some materials do not follow it and we call them non-ohmic conductors. I hope I helped! ^-^
The answer is the first one. That's because the general theory of relativity is the thing experiencing whatever is experiencing relative to something else. The second answer is just plain wrong. The third answer is just a constant, and doesn't relate to experiencing anything. And the fourth answer is a force between two objects, and it has no second comparison. The first answer is how a subject experiences two different things.
