Zoë sees Elmo skateboarding to her right at 0.75 c. Elmo takes a standard meterstick (i. e., rest length of 1 m), and throws it to his right. Elmo determines that the meterstick is moving at 0.5 c with respect to Elmo. What lengths do Elmo and Zoë measure for the meterstick? Justify your reasoning.

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.