<span>a+b= ?
3i +3j + (3i -3j) = ?
3i + 3j + 3i -3j =?
= 6i + 0j</span>
Endless movement between hot and cold will eventually mean the end of the universe. This law is about inefficiency, degeneration and decay. <u>The second law can be expressed in several ways, the simplest being that heat will naturally flow from a hotter to a colder body. At its heart is a property of thermodynamic systems called entropy.</u> Entropy basically means an increase in randomness. Hope this helps mate.
The trains take <u>57.4 s</u> to pass each other.
Two trains A and B move towards each other. Let A move along the positive x axis and B along the negative x axis.
therefore,

The relative velocity of the train A with respect to B is given by,

If the train B is assumed to be at rest, the train A would appear to move towards it with a speed of 170 km/h.
The trains are a distance d = 2.71 km apart.
Since speed is the distance traveled per unit time, the time taken by the trains to cross each other is given by,

Substitute 2.71 km for d and 170 km/h for 

Express the time in seconds.

Thus, the trains cross each other in <u>57.4 s</u>.
The right answer is
all of the above
good luck
Answer: Smoke is Abiotic because it is not a living thing.
Explanation: Hopefully this helps u. Have a great rest of your day. I hope this is the right answer