That depends on the direction of the velocity (which the question doesn't say).
Answer:
Explanation:
By Snell's law we know at the left surface
now we have
now on the other surface we know that
angle of incidence = 
so again we have
so we have
also we know that
By solving above equation we have
A "folk" remedy is something you choose to eat, take, or do,
in order to correct some health issue, because your friend,
your grandmother, your religion, your shaman, your astrologer,
or your medicine man says that it's the right thing to do.
It may or may not be effective, and it may or may not even be
safe. What distinguishes it from mainstream medicine is that
its practices are based on hearsay, and have not been subjected
to scientific methods of investigation and evaluation.
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applied forces would be push for example.
normal forces would seem to be a force such as gravity.
friction for example when you try to slide on carpet but the fabric or whatever its made of stops you.
