Question

The "Open" sign at your local deli flashes on and off all day long at 2.0 s intervals. The aliens spying on you from space are watching the same neon sign you are but they are moving towards Earth at a speed of 0.90c. How long is the interval flash (in s) for the aliens?

Answer 1

Interval t = 0.87 s

Step-by-step explanation:

Given:

t₀ = 2.0 s

V = 0.90c

_________

t - ?

Relativistic clock slowdown:

`t = t_0\cdot \sqrt{1-((V)/(c) )^2} \\`

`t = 2\cdot\sqrt{1 - ((0.90c)/(c))^2 } = 2\cdot√(1 - 0,90^2)= 2\cdot√(0.19) = 0.87 s`