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Let's do one more
example dealing

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with displacement,
velocity, and time.

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So we have if Marcia travels for
1 minute at 5 meters per second

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to the south, how much
will she be displaced?

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Let me do it this way.

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We know that velocity
is equal to displacement

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divided by time.

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And it's really, once
again, it is change in time.

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But we'll just say time.

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That's implicitly
change in time.

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And if you manipulate
this a little bit,

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you really just multiply
both sides by time.

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You just multiply both
sides by the variable t.

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You get displacement.

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Because this cancels out.

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You get displacement.

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And I'll flip this around.

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What's on the right-hand
side, I'll write on the left.

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So you get displacement
is equal to time

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times velocity or
velocity times time.

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Is equal to velocity times
time or velocity times

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change in time.

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So over here, they're
asking us for displacement.

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They're asking us how much
did Marcia get displaced?

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And they're saying that
she travels for 1 minute.

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So this 1 minute right over
here, this is her time.

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Sometimes you could view
that as her change in time.

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Or it really is
her change in time.

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If it said 0 minutes on her
stopwatch when she started,

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at the end it'll say 1 minute.

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Or if it said 5
minutes, if maybe it

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was 3:05 when she
started, it would be 3:06

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when she finished.

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So it was really
the change in time.

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Once again, I won't
write the delta there

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just because this is the way
you most frequently see it.

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But I want to tell
you that these

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are the same thing for the
purpose of this problem

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because sometimes you'll
see the delta there.

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So the 1 minute, so the t
right over here is 1 minute.

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At 5 meters per
second to the south.

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This right over here
is the velocity.

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They give us the magnitude,
which is 5 meters per second.

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Or you could say
that's the speed.

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And they also give us the
direction, to the south.

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So this right over here is 5
meters per second to the south.

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So we might just say, look, if
we want displacement, that's

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just going to be equal to 5
meters per second to the south

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times 1 minute.

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The problem here
is that when we're

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talking about
displacement, we're

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going to think about a magnitude
of how much it's moved.

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So it'll be a
distance of some kind.

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And some direction.

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We have our direction
here, but we

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don't want any
other units there.

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And if we just multiply
this over here,

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we have 1 minute over here.

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But we have seconds
in the denominator.

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You can't just cancel out
a minute and a second.

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So you can't just
say that you're

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going to get 5 and have
some weird thing here.

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So in order for it
to all work out,

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you have to either convert
the 5 meters per second to 5

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meters per minute.

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Or let me phrase
that another way.

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You have to convert
the 5 meters per second

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to some amount of
meters per minute,

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not 5 meters per minute.

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It's going to be different.

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Or you convert the
1 minute to seconds.

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So at least in my
mind, it's easier

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to convert 1 minute to seconds.

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So let's do that.

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So this is the same thing.

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1 minute times.

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And we want to get
rid of the minute.

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And the minute is essentially
in the numerator right now.

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We could put this over 1.

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But it's essentially
in the numerator.

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So we want to divide by minutes.

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And we want to
multiply by seconds.

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We want seconds
in the numerator.

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And so how many seconds
are there per minute?

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You have 60 seconds
for every 1 minute.

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And so you have a minute
cancelling out with

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the minutes.

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And so now you have
5 meters per second

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to the south times 60 seconds.

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This is now cool because you
have seconds and seconds.

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I wrote "sec" there,
but this is also sec.

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So now you have
seconds over seconds.

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Those cancel out.

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And so your
displacement is going

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to be equal to 5 times 60.

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And then your units
left are meters.

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All the time units have
cancelled out and then

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it's meters to the south.

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So meters to the south.

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And this is equal to 5 times
60 is 300 meters to the south.

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And we are done.

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That's how much she
has been displaced.

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If they just wanted
the distance,

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you could say that she
traveled 300 meters.

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Just that part.

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The magnitude of
the displacement,

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that is the distance
that she traveled.