Solving Relative Velocity Problems
Learning Objective
I can solve problems involving relative velocity in two dimensions.
Key Concepts
Relative velocity refers to the velocity of an object relative to the reference frame of the observer.
When a boat heads directly across a river, the resultant velocity is found by using the Pythagorean theorem to combine the boat's velocity and the river's velocity; the direction is found using trigonometry.
Perpendicular components of motion are independent of each other, meaning the river's southward velocity does not affect the time it takes for a boat to head eastward across the river.
Practice Questions
This lesson includes 8 practice questions to reinforce learning.
View questions preview
1. What does the term 'relative velocity' mean in the context of moving objects and observers?
2. A plane is flying north with a velocity of 300 km/h with respect to the air. The wind is blowing east at 60 km/h. What is the magnitude of the plane's velocity with respect to the ground?
3. A boat heads directly north across a river that is 200 meters wide. The boat's speed in still water is 5 m/s, and the river flows east at 2 m/s. What is the boat's resultant velocity with respect to an observer on the shore?
...and 5 more questions
Educational Video
Relative Velocity and River Boat Problems
The Physics Classroom