in 30 min, the boat goes 1/2 * (9-4)=2.5km
in the same time, the object goes 2km
so the distance apart is 4.5km
Now, going downstream, the relative velocity between the boat and object is 9km, so time=reldistance/relvel=4.5km/(9km)=30min
total distance relative to shore:
distance up+distance down
2.5km+ rate(time)=
2.5km+ 13(1/2)=9km
5. A boat capable of making 9.0 km/hr in still water is travelling upstream in a river
flowing at 4 km/h. An object lost overboard is not missed for 30 minutes.
(a) If the boat is then turned around, how long will it take to overtake the
floating lost object?
(b) What total distance will the boat travel relative to the shore from the
point of turnaround to the point of overtaking the object?
1 answer