falling_speed_of_petals.rb

=begin
When it's spring Japanese cherries blossom, it's called "sakura" and it's
admired a lot. The petals start to fall in late April.

Suppose that the falling speed of a petal is 5 centimeters per second (5 cm/s),
and it takes 80 seconds for the petal to reach the ground from a certain branch.

Write a function that receives the speed (in cm/s) of a petal as input, and
returns the time it takes for that petal to reach the ground from the same branch.

Notes:

The movement of the petal is quite compilcated, so in this case we can see the
velocity as a constant during its falling.
Pay attention to the data types.
If the initial velocity is non-positive, the return value should be 0
=end

def sakura_fall(v)
  return 0 if v.negative?
  400/v.to_f
end