00:04
So in this problem, we're going to be looking at average velocities.
00:08
And so let's just think about that quantity for a second, that average velocity.
00:17
We're going to be looking at the average distance over time.
00:30
So looking at part a, what quantities are we given? so we're given some distances and velocities.
00:43
Okay, so let's just think about, again, what we're trying to calculate.
00:53
So a total distance.
00:55
So i'm going to write that as d1 plus d2 because we're given two distances problem.
01:04
And so the denominator is a bit more complicated.
01:07
We need a time.
01:09
And so we use the distances that we were given for the numerator here.
01:13
And so we're left with these velocities.
01:15
So we're going to have to use the definition of velocity and convert that into a time.
01:21
And so if we write out the, equals d over t our definition of velocity we can rearrange things algebraically and we can express this as t equals d over v and so that's so that's sort of how we can convert the distances and velocities that were given into a time that's what we need in our denominator here so instead of writing t1 plus t2 we can express that as d1 over v1 plus d2 over v2.
02:03
So again, this quantity here is t1.
02:08
This quantity here is t2.
02:13
And so now we can plug in all of our values that we're given into this formula.
02:27
So these distances are both given in meters.
02:31
So just always be mindful of your units, of course.
02:42
And so just looking at this, the velocities are given in meters per second.
02:46
So it's good.
02:47
Sorry, that's 73 .2, not 7 .32.
03:08
And so that second velocity is 3 .05.
03:19
Okay.
03:21
So if you plug all of this into your calculator, you should get approximately 1 .74 meters per second.
03:33
Okay, great.
03:34
Moving on to part b.
03:38
So we're given some more quantities here.
03:40
And what are we given? we have times, and then we have velocities.
04:03
Okay, so thinking about our formula.
04:10
So okay, we're given times, that's straightforward to plug in.
04:13
We know that in our velocity formula, in the denominator, we have times.
04:17
So i'm just gonna write this as t1 plus t2.
04:20
Since again, we're given two times in the problem.
04:23
And so now you can see the other quantity that we're given is velocity.
04:26
We're looking to plug a distance into the numerator...