Math
posted by amy on .
This is also another problem that I'm having trouble on.
A motorboat can maintain a constant speed of 16 miles per hour relative to the water. The boat makes a trip upstream to a certain point in 20 minutes; the return trip takes 15 minutes. What is the speed of the current?
Also what would be the equation?
For this motion problem I only learned how to solve this with the distance and velocity given.
What would be the velocity? v16 and v+16 ?
Please help! Thank you.

If we calculate using velocity, we have to establish a positive direction. If velocity is measured as positive downstream, then
v = current velocity (downstream)
and
going upstream, the net velocity is v16, and downstream the net velocity is v+16.
Since the total distance travelled is zero at the end of the return trip, you can sum the distances travelled since the times are known.
(v16)*(20/60) + (v+16)*(15/60) = 0
Solve for v. I get between 2 and 2.5.