Answer:

Explanation:
From the question we are told that:
Velocity 
Force of friction f = 0
Angle 
Generally the equation for Radius of curvature is mathematically given by



Uranium-238 decays<span> by alpha emission </span>into<span> thorium-234, which itself </span>decays<span> by beta emission to protactinium-234, which </span>decays<span> by beta emission to </span>uranium<span>-234, and so on. The various </span>decay<span> products, (sometimes referred to as “progeny” or “daughters”) form a series starting at </span>uranium-238<span>.</span>
The number we need in order to answer the question belongs in the space between the words "is" and "of". You left that blank blank, so there really isn't any question here to answer.
HOWEVER ... the refractive index of a medium can never be less than 1.0 , so we know for sure that <em>choice-a can't be</em> the correct answer.
Magnets facing the same way <span />
There is no theoretical OR observational evidence for that statement.