Final answer:
To determine the speed of the jet ski relative to water, the concept of relative motion and vectors is used, applying trigonometry and the Pythagorean theorem.
Step-by-step explanation:
The student is asking about the speed of a jet ski relative to water, given its velocity relative to the ground and the speed of the river's current. To solve this, one must utilize vectors and the concept of relative motion. The velocities of the jet ski and the river current can be represented as vectors on an xy-coordinate system, and the actual velocity of the jet ski relative to the water (ground speed minus the current's speed) can be determined using trigonometry and the Pythagorean theorem.