Answer: Mid-ocean ridges are geologically important because they occur along the kind of plate boundary where new ocean floor is created as the plates spread apart. Thus the mid-ocean ridge is also known as a "spreading center" or a "divergent plate boundary." The plates spread apart at rates of 1 cm to 20 cm per year.
On the change in potential energy
The answer is a matter of opinion, and you're going to get different answers
from different people. Here's <u>my</u> take on it:
The writers, producers and advertising sponsors of these shows certainly
don't think they're boring. And <em><u>definitely</u></em> neither do the TV networks that
decide which ones to broadcast.
I'm not trying to say "The experts don't think they're boring, so you must
be wrong". I'm trying to say that different people have different opinions
about the same shows, and in <em>your</em> case,<em> you</em> find them boring.
My conclusion is this:
I think you're finding TV shows boring nowadays because you're growing
as a person. You've grown, developed, and matured to the point where
you're above the level of audience that the shows are pitched for. That's
a very good thing !
You're sad because you used to get pleasure and entertainment from TV,
and now it doesn't give you those things. That's like losing an old friend,
that you used to have such fun playing with, but he just doesn't do it for
you any more.
Now that you've grown up, you've made new friends. With them, you do
things that you wouldn't even understand with your younger friends. And
you develop new interests, like ... I don't know ... books, movies, hobbies,
your church, your profession, learning new things, developing new skills,
exercising your brain, writing, volunteer work, ham radio, building fine
furniture, singing, learning to write music, raising tropical plants, sculpture,
politics ... whatever turns you on. Some people never grow past the stage
where staring at the tube is all they need in life, because they don't have
what it takes to be interested in anything else. Those are the people that
TV is aimed at. But you have more, and that's why TV isn't enough for you.
There are other possible reasons why TV bores you. But until I know more
about you, I think it's a very, very good sign.
Before the engines fail, the rocket's altitude at time <em>t</em> is given by
and its velocity is
The rocket then reaches an altitude of 1150 m at time <em>t</em> such that
Solve for <em>t</em> to find this time to be
At this time, the rocket attains a velocity of
When it's in freefall, the rocket's altitude is given by
where 
is the acceleration due to gravity, and its velocity is
(a) After the first 11.2 s of flight, the rocket is in the air for as long as it takes for 
to reach 0:
So the rocket is in motion for a total of 11.2 s + 32.6 s = 43.4 s.
(b) Recall that
where 
and 
denote final and initial velocities, respecitively, 
denotes acceleration, and 
the difference in altitudes over some time interval. At its maximum height, the rocket has zero velocity. After the engines fail, the rocket will keep moving upward for a little while before it starts to fall to the ground, which means 
will contain the information we need to find the maximum height.
Solve for 
and we find that the rocket reaches a maximum altitude of about 1930 m.
(c) In part (a), we found the time it takes for the rocket to hit the ground (relative to ) to be about 32.6 s. Plug this into 
to find the velocity before it crashes:
That is, the rocket has a velocity of 196 m/s in the downward direction as it hits the ground.
