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So the majority of you saying its an attractive
potential energy.
The potential energy goes down when these two
things get closer together, so forces are acting to bring them closer together
and that means this one is being pulled that way in this is being pulled that
way which means they are attracting
each other. They're attracting each other
means the potential energy goes down when they get closer together.
Now this one you actually know, this is
at least somewhat physical. Here's the ball,
the earth is the other object, they
attract each other, which means the potential and he goes down
as they get closer together and that's what you see there.
Potential energy going down as the two things get closer together.
The force
on... the force on this one
is directly toward that, it's being pulled toward the other one.
The force on this one is directly toward that one.
It's another thing about
interactions that that you'll talk about a lot more in 7B
is that both objects feel
an interaction equally in oppositely, so this one
feels a force down and to the left
and this one feels the same magnitude force
but not down and to the left instead up and to the right.
Exactly equal and opposite forces.
Any questions about that one?
So I'm gonna skip ahead to this one.
Suppose the distance between these two objects is shown by
r, as shown to the right. Potential energy,
in other words, the interaction energy of this pair of objects,
okay, so now we're going to give it a complicated shape.
Here's the potential energy, here's the distance between the two objects here's
r. Here's r equals zero. Here's r equals
four Angstroms [where] the potential energy is zero.
It goes down and then it comes back up again.
Is the interaction between these two objects
attractive or repulsive? Are the two objects
attracting each other or repealing each other?
And I'll remind you
the force always acts to decrease
the potential energy.