00:01
In this question we've been told that a motorboat had a constant speed of 10 miles per hour relative to the water when going 51 miles upstream, then returning.
00:11
And the total time for the trip was 20 hours.
00:13
So we need to find out the speed of the current.
00:16
So first of all, we are going to record the information.
00:18
The velocity of the boat with respect to water is 10 miles per hour.
00:25
We need to find out the velocity of the current, which is unknown.
00:30
And the total time.
00:31
Is 20 hours and the distance for one side of the journey is 51 miles so first of all we are going to write down the equation for the total time taken so the total time is going to be equal to the time taken when traveling upstream and when it is when the boat returns so the time taken while traveling down stream so you're going to substitute this t with the expression using the formula s equals to vt.
01:17
So time is going to be equal to distance divided by the velocity.
01:22
In both cases, upstream and downstream, the distance is going to be the same 51 miles.
01:28
So 51 plus 51.
01:31
And it is going to be divided by the velocity...