closed and unsecure circuit
I think the first question is talking about the ionic compound Sodium sulfide and it’s formula is Na2S.
And for the second question, i’m pretty sure it’d be a positive charge
Answer:
The rate of change of the area when the bottom of the ladder (denoted by
) is at 36 ft. from the wall is the following:

Explanation:
The Area of the triangle is given by
where
(by using the Pythagoras' Theorem) and
is the length of the base of the triangle or the distance between the bottom of the ladder and the wall.
The area is then

The rate of change of the area is given by its time derivative


Product rule
Chain rule


In here we can identify
,
and
.
The result is then

Yes. If a downward force is created, it will be felt at the end of the rope as well.
That's good ! I never heard of that before. (Maybe because
I've never been stung by an ant.)
When an ant bites or stings, it injects a tiny amount of 'formic acid'
into your skin. Soon, the formic acid itches, burns, and stings, and
after a while, a little piece of skin dies and falls off. Some people
are seriously allergic to it, and it can make them really sick.
'Acids' and 'bases' are opposites, and one can neutralize (cancel out)
the other. Tony is putting a weak 'base' on the sting, to neutralize the
formic acid that the ant left him as a little gift.