Three observers watch the same puck on a nearly frictionless air table: • Observer G…
PHYSICS · Single correct · AP · Physics 1: Algebra-based · Force and Translational Dynamics · Force and Translational Dynamics
Problem
Three observers watch the same puck on a nearly frictionless air table:
• Observer G stands on Earth’s surface.
• Observer R rides in a railcar that moves east at 5m/s and is speeding up at 1m/s2 eastward.
• Observer S rides on a second railcar that moves east at a constant 5m/s.
At the instant the puck is released from rest relative to Earth, it is adjacent to both railcars. Which of the following statements is correct?
(a) All three observers are in inertial frames, because each can apply Newton’s laws by accounting only for relative motion.
(b) Observers G and S are in inertial frames; Observer R is not, because R sees the puck accelerate without any real force acting on it.
(c) None of the observers is in an inertial frame, because Earth rotates and therefore accelerates.
(d) Observers G and R are in inertial frames; Observer S is not, because S sees the puck move backward inside the car.