1) A boat is able to move through still water at 20m/s. It makes a round trip to a town 3.0 km
upstream. If the river flows at 5m/s, the time required for this round trip is:
2) A boat is traveling upstream at 14km/h with respect to a river that is flowing at 6 km/h (with
respect to the ground). A man runs directly across the boat, from one side to the other, at
6km/h (with respect to the boat). The speed of the man with respect to the ground is:
Thanks!
upstream. If the river flows at 5m/s, the time required for this round trip is:
2) A boat is traveling upstream at 14km/h with respect to a river that is flowing at 6 km/h (with
respect to the ground). A man runs directly across the boat, from one side to the other, at
6km/h (with respect to the boat). The speed of the man with respect to the ground is:
Thanks!

1) Upstream time. (20  5) = 15kph., distance = 3km.
Time taken = (3/15) = 0.2 hr.
Downstream time. (20 + 5) = 25kph. Distance = 3km.
Time taken = (3/25), = 0.12 hr.
Total time = 0.32 hr., = 18 mins, 12 secs.
2) Forward speed = (14  6) = 8kph.
Speed of man with respect to the ground = sqrt. (8^2 + 6^2), = 10kph.
Time taken = (3/15) = 0.2 hr.
Downstream time. (20 + 5) = 25kph. Distance = 3km.
Time taken = (3/25), = 0.12 hr.
Total time = 0.32 hr., = 18 mins, 12 secs.
2) Forward speed = (14  6) = 8kph.
Speed of man with respect to the ground = sqrt. (8^2 + 6^2), = 10kph.