Mod 7 Q (1 Viewer)

[howcanibesmarter]

Hi can someone explain this question? Answer is C

 

[chilli 412]

as quoted from some guy on the ********** discord:

1. Recognise the distance travelled by the astronaut is 8 ly (0.8*10).
2. Recognise that light from Earth will therefore take 8 years to travel the distance to astronaut.
3. Therefore the light that he will see, will be the light from when he had been travelling for 2 years.
4. Use time dilation on the 2 years and you will get 1.2 years. (Or could use length contraction on the 8 ly = 4.8 ly, therefore time elapsed = 6-4.8 = 1.2).

this question caused a ton of controversy over there lmao and people ended up agreeing that the correct answer should actually be 3.33 years (see below)

 

[jimmysmith560]

Fun fact: this question (Question 5 from the 2003 Physics HSC exam) had 6.0 as the correct response, which happens to be (A) in OP's version of the question. Due to its ambiguity, it was ignored during the marking, meaning that it ended up not contributing to students' total marks.

 

[howcanibesmarter]

as quoted from some guy on the conquerhsc discord:

1. Recognise the distance travelled by the astronaut is 8 ly (0.8*10).
2. Recognise that light from Earth will therefore take 8 years to travel the distance to astronaut.
3. Therefore the light that he will see, will be the light from when he had been travelling for 2 years.
4. Use time dilation on the 2 years and you will get 1.2 years. (Or could use length contraction on the 8 ly = 4.8 ly, therefore time elapsed = 6-4.8 = 1.2).

this question caused a ton of controversy over there lmao and people ended up agreeing that the correct answer should actually be 3.33 years (see below)

View attachment 38770
View attachment 38771

yea cus there was a question similar to this, and some people did what the 1.2 years solution did, while others just plugged it into the formula.