Kinematics Castle: River Crossing
boat velocity relative to the waterwater velocity relative to the bankboat velocity relative to the bank (the sum)
PREDICT drift downstream (m):
How this connects to AP Physics 1 (Topic 1.4, Reference Frames and Relative Motion): velocities depend on the reference frame. The boat's velocity relative to the ground is the vector sum of its velocity relative to the water and the water's velocity relative to the ground. Only the across-river component carries you across, so the crossing time depends on that component alone. Switch to WATER view to see the same trip from a frame moving with the current.