How fast will Louisa Lane fall into her Death?

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Lex Luthor has had it with Louise Lane, so he shoves her off his jet from an altitude of 20000ft. Lex is what u call Class - he takes a selfie and tweets the thing. The news catches Batman in the Bat-toilet (not sure that's an upside-down toilet) in the Batcave some 15 miles away from the drop point. Anyway, he figures He will be scrubbing Louisa off the pavement in about 5 minutes: 1 more minute on the Bat-toilet, 1 more to get the Batmobile running, then yup, no 'problemo'. He will be there right when she hits. Superman will not be happy to get this tweet. How fast is Louise falling to her death (in ft/s)? (note: this one does not follow physics rules strictly) At what speed did the Batmovil travel towards the splash zone (in mi/h)?