L= Lp - 13.7*Lp/100 = Lp-0,137Lp = 0,8613Lp
⇒L/Lp = 0.8613
From the formula above L/Lp = √(1-v^2/c^2)
(L/Lp)^2 = 1 - (v^2/c^2)
v^2/c^2 = 1 - (L/Lp)^2
v/c = √[1 - (L/Lp)^2]
v = c √[1-(L/Lp)^2]
v =c√[1-0.8613^2] = 0.508c
In the vacumm speed of light, c, is approx 300,000,000 m/s
v =0.508 (300,000,000m/s) =152,400,000 m/s
Please, let me know if this helped you.
