If a clock in an airplane is found to slow down by 5 parts in 1013, (i.e., ∆t/∆to = 1.0 + 5.0 × 10. −13), at what speed is the airplane traveling? (Hint: You might need to use an expansion for y)

I am not sure which equation to use can someone please help me.
L=L0(square root 1-v'2/c'2)
&=1/square root 1-v'2/c'2

2 answers

use the second equation.
The first equation lhas to do with length contraction. Use the second one

Set 1 + 5.0*10^-13 = 1/sqrt[1 - (v/c)^2]
Then solve for v, or v/c