Special relativity question!

These can be fun and at the same time frustrating!
Anyway, can anyone have a look at Number 12 on the:

special relativity question list

If the speed of the Klingon ship relative to the enterprise is zero, how can its length as observed on the enterprise, be different to its proper length? (No speed => no lorentz transformation)

thanks again

Reply 1

nikk

15

tsunami

These can be fun and at the same time frustrating!
Anyway, can anyone have a look at Number 12 on the:

special relativity question list

If the speed of the Klingon ship relative to the enterprise is zero, how can its length as observed on the enterprise, be different to its proper length? (No speed => no lorentz transformation)

thanks again

As the klingon ship and the enterprise are not moving relative to each other, both parties would observe each others ships to be the normal size. If another ship came along that was travelling much faster / slower relative to them then they would observe the length to be different.

Reply 2

Nylex

10

I don't get Special Relativity :frown:

.

Reply 3

tsunami

OP

Nylex

I don't get Special Relativity :frown:

.

yes we should campaign to get SR removed from physics courses lol :biggrin:

Reply 4

chrisbphd

2

tsunami

These can be fun and at the same time frustrating!
Anyway, can anyone have a look at Number 12 on the:

special relativity question list

If the speed of the Klingon ship relative to the enterprise is zero, how can its length as observed on the enterprise, be different to its proper length? (No speed => no lorentz transformation)

thanks again

I can't access this from cambridge!

Reply 5

elpaw

15

tsunami

These can be fun and at the same time frustrating!
Anyway, can anyone have a look at Number 12 on the:

special relativity question list

If the speed of the Klingon ship relative to the enterprise is zero, how can its length as observed on the enterprise, be different to its proper length? (No speed => no lorentz transformation)

thanks again

I thought i had seen that question before......
what college are you in?

Reply 6

elpaw

15

chrisbphd

I can't access this from cambridge!

a bit of ox/bridge rivalry there..... the domain "ox.ac.uk" has probably been banned by the cambridge computing authorities

Reply 7

elpaw

15

tsunami

These can be fun and at the same time frustrating!
Anyway, can anyone have a look at Number 12 on the:

special relativity question list

If the speed of the Klingon ship relative to the enterprise is zero, how can its length as observed on the enterprise, be different to its proper length? (No speed => no lorentz transformation)

thanks again

anyway, in answer to your first question, same speed does not equal same velocity. you have to use the addition of velocities that you worked out for question 12.

Reply 8

tsunami

OP

elpaw

anyway, in answer to your first question, same speed does not equal same velocity. you have to use the addition of velocities that you worked out for question 12.

i actually was refering to 13 and not 12, but are you saying that the enterprise and the klingon ship are moving away from each other at the same speed 0.2c so effectivly the relative vel as observed by enterprise is 0.4c??

Reply 9

elpaw

15

tsunami

i actually was refering to 13 and not 12, but are you saying that the enterprise and the klingon ship are moving away from each other at the same speed 0.2c so effectivly the relative vel as observed by enterprise is 0.4c??

yes, except (if you have done q12) it isnt 0.4 c, because in relativity velocities don't add up that simply. from q12, V = (v1 + v2)/(1 + v1v2/c²) = 0.3846 c and use that to work out the length

Reply 10

tsunami

OP

elpaw

yes, except (if you have done q12) it isnt 0.4 c, because in relativity velocities don't add up that simply. from q12, V = (v1 + v2)/(1 + v1v2/c²) = 0.3846 c and use that to work out the length