Practice describing and calculating relative motion using different reference frames, velocities, and directions.
Read each problem carefully. Use signs or directions to show your chosen reference frame. Show your work in the space provided.
Describing motion from different points of view
Physics - Grade 9-12
- 1
A student stands on a sidewalk and watches a bus travel east at 12 m/s. A passenger on the bus walks toward the front of the bus, also east, at 1.5 m/s relative to the bus. What is the passenger's velocity relative to the sidewalk?
- 2
A train moves north at 25 m/s relative to the ground. A person on the train walks south at 2 m/s relative to the train. What is the person's velocity relative to the ground?
- 3
Two cars travel on a straight highway. Car A moves east at 30 m/s, and Car B moves east at 22 m/s. What is the velocity of Car A relative to Car B?
- 4
Two runners move toward each other on a straight track. Runner A moves east at 6 m/s, and Runner B moves west at 5 m/s. What is Runner A's velocity relative to Runner B?
- 5
A boat travels east across a river at 4 m/s relative to the water. The river current flows east at 1.5 m/s relative to the shore. What is the boat's velocity relative to the shore?
- 6
A boat points straight north and moves at 3 m/s relative to the water. The river current moves east at 4 m/s relative to the shore. What is the boat's speed relative to the shore?
- 7
A plane flies north at 80 m/s relative to the air. A wind blows south at 15 m/s relative to the ground. What is the plane's velocity relative to the ground?
- 8
A plane flies east at 120 m/s relative to the air. A wind blows north at 50 m/s relative to the ground. What is the plane's speed relative to the ground? Round to the nearest meter per second.
- 9
A skateboarder rides west at 7 m/s relative to the ground. A friend jogs west at 3 m/s relative to the ground. From the friend's reference frame, what is the skateboarder's velocity?
- 10
A ball is thrown straight up inside a train moving at constant velocity. Ignore air resistance. Describe the ball's motion as seen by a passenger on the train and as seen by an observer standing beside the tracks.
- 11
A cyclist moves east at 10 m/s relative to the ground. A car moves west at 20 m/s relative to the ground. If east is positive, what is the velocity of the cyclist relative to the car?
- 12
A moving walkway in an airport carries people east at 1.2 m/s relative to the floor. A traveler walks west on the walkway at 0.8 m/s relative to the walkway. What is the traveler's velocity relative to the floor?