An object is thrown up in the air and then Cozumel vacation it was thrown it is in the air for total of 3.2 seconds how do you find the final velocity

How does an observation about an object differ from an inference about that object

If the work required to stretch a spring 3 ft beyond its natural length is 15 ft-lb, how much work is needed to stretch it 27 in. beyond its natural length?

In a hydrogen molecule there are a total of four charges, 2 protons in the two nuclei, and 2 electrons. how many unique charge-pairs are there (without double counting)?