Two swimmers A and B, of weight 190 lb and 125 lb, respectively, are at diagonally opposite corners of a floating raft when they realize that the raft has broken away from its anchor. Swimmer A immediately starts walking toward B at a speed of 2 ft/s relative to the raft. Knowing that the raft weighs 300 lb, determine (a) the speed of the raft if B does not move, (b) the speed with which B must walk toward A if the raft is not to move.

a) 0.618 ft/s

b) 3.04 ft/s

Explanation:

Givens:

Weight of swimmer A = 190 Ib.

Weight of swimmer B  = 125 Ib.

Weight of the raft = 300 Ib.  

Swimmer A walks toward swimmer B relative to the raft with a speed

= 2 ft/s

a) Conservation of linear momentum

Since swimmer B does not move  

Substitute from (2) and (3) into (1)

b) if the raft not to move

from (2)

substitute in (1)

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.

so easy. just google the electromagnetic waves and it’ll pop up.