Relative Time and Distance

Robert: College Student: Relative Time and Distance

Orlav, his professor, wrote the following to contrast the two situations.

Person on train: train speed + walking speed during 1 hour trip train speed (at 200 mph) + steps (at 2 mph)

◦ 202 miles traveled

◦ feels like 2 miles of walking

Person on tracks: walking speed for 1 hour walking speed (at 2 mph)

◦ 2 miles traveled

▪ feels like 2 miles of walking

Time to travel 2 miles @ 202 mph (train):

Time = 2 miles / 200 mph = approximately 1/100th of an hour

◦ Time = 1/100th of 60 minutes

▪ Time = .6 minutes or 36 seconds

Time to travel 2 miles @ 2 mph (walking along tracks):

Time = 2 miles / 2 mph = 1 hour

◦ Time = 60 minutes * 60 seconds

▪ Time required = 3,600 seconds

Orlav peered over his reader glasses. “So why not ask how many miles away in Space?” he asked the class. He clarified. “Like 4,000,000 miles away?”

Sarah cautiously raised her hand, “Because we know that everyone's perspective of units of distance is relative to how fast they’re traveling through Space. Miles per hour, for example.” She continued on more confidently, “And that means that every planet has its own perspective of how many miles you could travel in an hour … because each planet travels around the sun at a different rate.”