Answer:
1. What happens when air is heated or cooled? ... So air, like most other substances, expands when heated and contracts when cooled. Because there is more space between the molecules, the air is less dense than the surrounding matter and the hot air floats upward.
Step-by-step explanation:
Hope this helps
Answer:
where is the tension.......?
Step-by-step explanation:
Answer:

Step-by-step explanation:
A function satisfying the equation
is said to be an even function. This denomination comes from the fact that the same relation is satisfied for functions of the form
with
even. Observe that if
is twice differentiable we can derivate using the chaing rule as follows:
implies 
Applying the chain rule again we have:
implies 
So we have that function
is also an even function.
c is the answer because negative numbers have to go first