Time contraction question (1 Viewer)

[chingyloke]

This is out of the success one book.

An alarm clock is set to go off in one hour when it is at rest. The alarm clock is set in motion at .95 times the speed of light (0.95 c)

a) calculate how long it would take the alarm to go off for stationary observes watching it move away at .95c


so i put it into the formula

Tv=To/sqroot(1-v^2/c^2)

Tv=60 (minutes) / sqroot (1-0.95^2)

Tv= 192 minutes

but the answers say 615 minutes. am i missing something? or is the book wrong?

 

[shady145]

2001 paper q 21

i see their working out and just put their numbers in and it come out with 615.
but i think there is a mistake coz they left it in minutes.
converting the 60 to 3600 seconds i get your answer. i will ask my teacher tomorrow. but i think they made a mistake because we always work with seconds.

 

[shady145]

my teacher said the book is definetely wrong.

 

[darkchild69]

2001 paper q 21

i see their working out and just put their numbers in and it come out with 615.
but i think there is a mistake coz they left it in minutes.
converting the 60 to 3600 seconds i get your answer. i will ask my teacher tomorrow. but i think they made a mistake because we always work with seconds.

Wouldnt make a difference whether it was in hours or minutes, it would just change the resulting units for you answer, but essentially would come to the same answer.

The answer in the back of the book is wrong.

They forgot to square root the denominator before dividing it

Tv=To/sqroot(1-v^2/c^2)

Tv=60 (minutes) / sqroot (1-0.95^2)

Tv= 192 minutes

is correct, they didnt do the underlined and bold bit

A lot of texts have this same mistake!


btw, shady.. top choice of song in your sig mate I had a few drinks with bone thugs on a couple of occasions, top blokes!

 

[shady145]

btw, shady.. top choice of song in your sig mate I had a few drinks with bone thugs on a couple of occasions, top blokes!

o haha kool.

can you please explain the underlined root part

 

[chingyloke]

ahhh that's great. i hate it when texts are wrong in the back. it stresses me out. lol

i think he means that to get the text's answer you just leave out the square root

so like Tv=60/(1-.95^2)
Tv=615 minutes...which is the texts answer

 

[shady145]

o
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