Free `^238 U` nuclei kept in a train emit alpha particles. When the train is stationary and a uranium nucleus decays, a passenger measues that the separation betwee the alpha particle and the recoiling nucleus becomes `x` in time `t after the decay. If a decay takes place when the train is moving at a uniform speed `v`, the distance between the alpha particle and the recoiling nucleus at a time `t` after the decay, as measured by the passenger will be

Options

A. `x + vt`
B. `x - vt`
C. `x`
D. depends on the direction of the train

Answer

C