question: If the condition/parameter is rapidity of 1 hyperbolic radian, what is the proper velocity w dx/dτ in units of c?
answer: SELECT proper_velocity_w_dx_dτ_in_units_of_c FROM table_15314901_1 WHERE condition_parameter = "Rapidity of 1 hyperbolic radian"
context: CREATE TABLE table_15314901_1 (proper_velocity_w_dx_dτ_in_units_of_c VARCHAR, condition_parameter VARCHAR)