(2) 16 year old Kasey sends her 48 year old dad, Steve, on a trip to to explore the universe. When Steve returns,
he has aged 10 years, and is shocked to discover that Kasey is now the same age he is! How fast was Steve's
spaceship traveling while he was away? (Give your answer in terms of a fraction of the speed of light.)

Respuesta :

The speed of the spaceship is 0.971c

Explanation:

Since Steve is moving at a speed close to the speed of light, the time observed by Kasey will be dilated, according to the equation

[tex]T' = \frac{T}{\sqrt{1-(\frac{v}{c})^2}}[/tex]

where

T' is the time measured by Kasey

T is the time measured by Steve

v is Steve's speed

c is the speed of light

Here we have:

T = 10 years (time measured by Steve)

When Steve is back, his age is 48 + 10 = 58 years. Kasey has now the same age, so the amount of time passed according to Kasey is

[tex]T' = 58 -16=42 y[/tex]

Substituting into the equation, we can fidn the speed of Steve's spaceship:

[tex]\sqrt{1-(\frac{v}{c})^2}=\frac{T'}{T}\\1-(\frac{v}{c})^2=(\frac{T'}{T})^2\\v=c\sqrt{1-(\frac{T'}{T})^2}=c\sqrt{1-(\frac{10}{42})^2}=0.971 c[/tex]

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