To calculate the speed and velocity of the Ann`s we use the formula,

Here, d is distance and t is time and v if we take it with direction then it is called velocity and if we take it without the direction then it is called speed.
Given
and
.
Substituting these values in above equation we get

As Ann walked towards south direction therefore, Ann`s velocity is 3 mi/h south and her speed is 3 mi/h .
Answer:
Less than a quarter of Earth's surfaces are dry, ice free lands
Buhrs atomic model differed from ruthofords because it explained that electrons exist in specified energy levels surrounding the nucleus. This means that, Ruthoford believed that electrons can't do very much. However, Buhrs' model showed that electrons are much more powerful than anyone else believes they can be.
“Most climate scientists
believe that there is evidence that explains global warming” is best supported by
this study.
The drastic increase in the emission of CO2 (carbon dioxide)
within the last 30 yearscaused<span> by burning fossil fuels has been identified as
the major </span>reason<span> for
the change of temperature in the atmosphere (click the following link for a
summary and graphs about the </span>cause<span> and
effects of </span>global warming).
The correct answer between all
the choices given is the last choice or letter D. I am hoping that this answer
has satisfied your query and it will be able to help you in your endeavor, and
if you would like, feel free to ask another question.