Practice Reference Frame in Physics
Use these practice problems to test your method after reviewing the concept explanation and worked examples.
Quick Recap
A coordinate system used to describe positions and motions, relative to an observer.
Are you 'moving' on a train? Depends on whether you ask someone on the train or the platform.
Example 1
easyTrain A moves east at 30 \text{ m/s} and Train B moves east at 20 \text{ m/s}, both relative to the ground. What is the velocity of Train A relative to Train B?
Example 2
mediumA boat travels at 5 \text{ m/s} relative to the water, heading directly across a river that flows at 3 \text{ m/s}. What is the boat's speed relative to the ground, and at what angle does it actually travel?
Example 3
mediumCar A travels north at 25 \text{ m/s} and Car B travels south at 20 \text{ m/s}, both relative to the ground. What is the velocity of Car A as seen by Car B?
Example 4
hardA plane flies at 250 \text{ m/s} due north relative to the air. A wind blows at 50 \text{ m/s} from the west (toward the east). What is the plane's ground speed and actual direction of travel?