00:01
This problem we're told a person runs at a speed of 4 meters per second.
00:08
We'll call this v1, a distance of 60 meters.
00:15
We'll call that x1.
00:17
And the runner now has a velocity of 6 meters per second, which i'll call v2.
00:24
And this goes on for another 60 meters.
00:28
So call that x2.
00:30
We want to calculate that.
00:32
The average speed of the runner.
00:36
So to do this, we the equation for average speed, which i can just call s for average speed, is equal to xt, which is the total distance at the runner travels, divided by delta t.
00:53
So delta t is a time interval, t1 of the first velocity, plus the time interval of t2 of the second velocity.
01:03
And for distance travel, we can just add up 60 plus 60, which we get 120.
01:08
So what we need to find is t1 and t2.
01:12
So let's look at t1 first.
01:15
So we can use the equation for velocity for t1.
01:18
So we have v1 is equal to x1 divided by t1.
01:24
Now we're looking for t1...