Question

4. -1 points Tipler6 3.P058 My Two boat landings are 1.0 km apart on the same bank of a stream that flows at 1.8 km/h. A motorboat makes the round trip between the two landings in 50 minutes. What is the speed of the boat relative to the water? km/h eBook 5. O -11 points Tiplers 3PO7S My In the figure below, what is the minimum initial speed of the dart if it is to hit the monkey before the monkey hits the ground, which is 10.2 m below the initial position of the monkey, if x is 42 m and h 9 m? (Ignore any effects due to air resistance.) m/s

Answer 1

4)

v=speed of boat in still water

V= speed of current = 1.8 km/h

using dist = speed x time

speed going with current = v+1.8

speed going against current = v-1.8

time downstream = 1.0 km/(v+1.8)

time upstream = 1.0 km/(v-1.8)

total time = time down + time up = 50 min (=0.833 hrs)

total time = 0.833 hrs = 1/(v+1.8) +1/(v-1.8)

0.833=2v/(v^2-3.24)

0.833 v^2 - 2v – 2.7 = 0

v = 3.36 km/hr