How long will it take for a sound impulse to travel through a copper rod 25 kilometers long?

By conducting exhaustive, high-intensity online research for about 15 seconds, I found a source that says the speed of sound in copper is 4600 m/s.  (You could easily have completed the same research project in about 1/3 of the time it took you to type and post the question here.)

Time it takes = (distance) / (speed)

Time = (25,000 meters) / (4600 m/s)

Time = (25 / 4.6) km-sec/km

Time = 5.43 seconds

a small object of mass 3.66 g and charge -17.6 µc is suspended motionless above the ground when immersed in a uniform electric field perpendicular to the ground. what are the magnitude and direction of the electric field?

what are the statements? x