A boat travels upstream and after one hour has gone 10 km. the boat next travels downstream and after one hour has gone 18km. if the boats speed relative to the water is constant, what is the speed of the river

4 km/h

Explanation:

Let the boat's speed relative to the water be u and the speed of the water be v (both in km/h)

upstream: boat's speed = u - v

during t = 1 hour, the distance is (u - v) * 1 = 10            (1)

downstream: boat's speed = u + v

during t = 1 hour, the distance is (u + v) * 1 = 18          (2)

(2) - (1): 2v = 18 - 10 = 8, so v = 4 km/h

v=ir = 3x15 =45 v

jupiter is the largest planet in our solar system, having a mass and radius that are respectively, 318 and 11.2 times that of earth. suppose that an object falls from rest near the surface of each planet and that the acceleration due to gravity remains constant during the fall. each object falls the same distance before striking the ground. determine the ratio of the time of fall on jupiter to that on earth.