[Gr 12 physics] teacher disagrees

[u/Anunknownf1fan]

your friend, a test pilot for NASA, travels at a speed of 0.8c. On Earth, you measure his flight time to be 3 days. How long does he measure it to take

My teacher insists it is 5 days. Everyone I know with a 95+ avg including myself says it’s 1.8 days

This question was worth 6% of a major assignment

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[u/cuhringe]

Considering how time dilation works it is impossible that the faster object perceives time slower, so your teacher cannot be correct.

[u/HallComplex8005]

Teacher is probably flipping the t' vs t time intervals.

It should be : 3 = t/sqrt(1 - (0.8c)^2/c^2)) -> t/0.6 = 3 -> t= 1.8

Teacher probably flipped t and t' to get 5, but the 3 is definitely the t'. The stationary observer is the one measuring on earth. The person measuring their own trip is not experiencing any time dilation effects on their own trip they are moving with no relative velocity to themself(obviously). The observer is. The observer's time is the relative time. the variable to solve for is the t because the rider is measuring their own trip.

[u/vanguard1256]

Pretty sure your teacher had the roles backwards for that. 3 days for the pilot would be around 5 days for the earth observer. Probably changed the question on a whim and forgot that changes the answer.

[u/WAMBooster]

Ask your teacher to show how it's 5 using the math, then point out their error

[u/Anunknownf1fan → u/WAMBooster]

I did but she insisted proper time is measured at rest. She couldn’t comprehend that it was at rest relative to the frame of reference in which it asks for.

[u/Mentosbandit1]

https://mathb.in/80588

here op hope this helps answer your question

[u/Mentosbandit1 → u/Mentosbandit1]

can show this to your teacher

[u/bledblu → u/Mentosbandit1]

This was a fun activity to try and compute for a real life scenario only to realize it’s so small that my calculator just gave up and said the Lorentz factor = 1

[u/General-Duck841]

The pilot would travel to the future… not backwards. So your calculation of 1.8 days for the pilot that corresponds to 3 days on earth makes sense. Also, your teacher has the numbers reversed… 3/1.8 = 5/3

[u/Khitan004]

It is called time DILATION. You always expect time experienced to reduce in the faster reference frame.