Question

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? v-16 and v+16 ?

Please help! Thank you.

Answer 1

If we calculate using velocity, we have to establish a positive direction. If velocity is measured as positive <i>downstream</i>, then
v = current velocity (downstream)
and
going upstream, the net velocity is v-16, 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.

(v-16)*(20/60) + (v+16)*(15/60) = 0

Solve for v. I get between 2 and 2.5.