Why does an object fall straight to the ground when it is inside a closed car at 60mph? Well the answer is that the air pressure is different inside then outside. But what if you drop an object in a bus with all the windows open (so the air pressure will be the same as it is outside)and drop an object to the ground from a couple of feet above the ground. Will the object still fall to the ground in a straight line or will it fall in a slight angle? I would really like to know.

Your biggest fan.

It would still fall straight down. If you are on a bus going 60mph, then you and whatever you are carrying are also traveling at 60mph. Windows up/down wouldnt make a difference unless whatever you are dropping is light enough to be affected by the wind coming from the windows.