The River
Boat
A GIF Animation
Observe the motion of the river boats below. In each case, the
boat is heading across the river. In the top case, the
presence of a current causes the boat to travel downstream as it
simultaneously moves across the river; the result is that it reaches
the opposite shore at a point downstream from where it started. In
the bottom case, the absence of a current means that the boat moves
straight across the river; it ultimately reaches a point on the
opposite shore directly across from where it started. It is important
to note that the current is what carries the boat down the stream; it
is not the motor of the boat that provides its downstream motion.
Assuming that in each case the motor of the boat propels it
across the river with the same force, in which case (with or without
a current) will the boat make it across the shore the soonest? Make
your observation in the above animation to find out. You might
observe something other than you expect.
For more information on physical descriptions of motion,
visit
The
Physics Classroom. Specific information is available there on the
following topics:
This page was created by
Tom
Henderson of
Glenbrook South
High School.
Comments and suggestions can be sent by e-mail to
Tom
Henderson.
This page last updated on 2/26/97.