A windowless spacecraft far from any planets accelerates at 5m/s2 in the +x direction. An astronaut simultaneously releases a steel ball and a plastic ball from rest relative to the spacecraft’s floor. Which of the following outcomes is most consistent with the equivalence principle?
a) Both balls accelerate toward the rear, and the steel ball’s acceleration is greater because its mass is larger.
b) Both balls accelerate toward the rear of the spacecraft with acceleration 5m/s2.
c) Both balls remain floating where they were released.
d) Both balls accelerate toward the rear of the spacecraft with acceleration 9.8m/s2.