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Topic 1.4: Practice Sheet — Reference Frames and Relative Velocity

Name: _______________________________ Date: _______________ Period: ______

Directions: For reasoning questions, write full sentences. For calculations, show your work and state your sign convention. Circle or box final numeric answers.

Warm-Up Level (straightforward, one-step)

  1. A passenger on a smoothly cruising ship bounces a basketball on the deck. Describe what the ball does, from the passenger's point of view.
  2. A moving walkway moves at 1.5 m/s. A person walks the same direction at 1.0 m/s relative to the walkway. Find their velocity relative to the ground.

Standard Level (multi-step, matches typical AP Classroom depth)

  1. A cruise ship cruises at 22 mph. A passenger walks toward the stern (opposite the ship's direction) at 2 mph relative to the ship. Find the passenger's velocity relative to the water.
  2. A student on a train tosses a pencil straight up and catches it. Someone on the platform outside watches the same toss. Describe what each observer sees, and explain why they're different even though it's the same event.
  3. Two trains approach each other on parallel tracks: Train A at +30 m/s, Train B at −25 m/s. Find Train B's velocity relative to a passenger on Train A.

AP-Level (multi-part: calculate + justify/represent/predict-a-change)

  1. A moving walkway at the airport moves at 2 m/s. Passenger 1 stands still on it. Passenger 2 walks the same direction at 1.3 m/s relative to the walkway. a) Find each passenger's velocity relative to the ground. b) Justify why Passenger 1, who isn't walking at all, still has a nonzero velocity relative to the ground.
  2. A classmate claims: "If two cars are both driving at 60 mph in the same direction on the highway, their relative velocity to each other is 120 mph." Explain what's wrong with this claim, and state the correct relative velocity.

Progress Check Style (evaluate the method — AP Classroom format)

  1. A fly is buzzing around inside a car's cabin while the car cruises at a constant 60 mph down a straight highway. Which of the following correctly predicts what a passenger inside the car observes about the fly's motion? (A) The fly appears to move at 60 mph plus its own buzzing speed, since the car is moving. (B) The fly's motion looks completely normal, the same as if the car were parked, since the passenger shares the car's constant-velocity frame. (C) The fly appears to lag behind and drift toward the back of the car the whole time. (D) The fly's motion cannot be predicted without knowing the car's exact speed.

Keep this sheet — it's part of your semester study materials, same as your Concept Sheets.