Ametallic laboratory spring is typically 5.50cm long and 0.140 cm in diameter and has 50.0 coils. if you connect such a spring in an electric circuit, how much self-inductance must you include for it if you model it as an ideal solenoid?

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.