0

A swimmers speed along the river is 20 km/h and upstream is 8 km/h. Calculate the velocity of the stream and the swimmers possible speed in still water.

I understand what the variables are and I understand what it is asking to find, but what I'm having trouble with is putting together an equation/formula that will help solve the problem.

alexsphysics
  • 3

1 Answers1

0

The formula here is not that important. Knowing that the velocities ADD when swimming downstream and SUBTRACT when swimming upstream is the main lesson of this problem.. Using this you get two equations Vdownstream = 20 m/sec = Vswimmer + Vriver and upstream we get Vupstream = 8 m/sec = Vswimmer - Vriver.

Simplifying these we get Vswimmer + Vriver =20 and Vswimmer - V river = 8

Now adding we get 2Vswimmer = 28 so Vswimmer = 14 m/sec

You can also subtract the 2 equations and get 2Vriver = 12 so Vriver = 6

Natsfan
  • 2,652