Hi Physics graduates,
Could someone with a degree in physics please answer this for me. I did some physics 30+ years ago, and I'm having a disagreement with a friend on this issue, and would like some clarification, please.
If an aircraft was to take off from some point (say my house) on the earth, thrust directly upwards to say 30,000 feet, then hover there for say 5 minutes, then come directly down, then in theory, assuming no "winds", it would land (approximately*) back at my house. Right?
I would have thought the main contributor to the "horizontal" movement (which keeps the aircraft above my house), is the momentum it had before it even took off.
I would have thought a secondary contributor would be the "horizontal" movement of the atmosphere which is basically rotating with the earth. As the craft gains altitude, it would require more “horizontal” velocity for it to keep up with the earth, because its radius from the centre of the earth would have increased. The movement of the atmosphere would act like a wind against it, and help to carry it along (though there could be some delay in the aircraft catching up, hence the "approximately*" above).
My questions are:
Q1. Does gravity contribute to anything to the "horizontal" movement of the aircraft, or does it only prevent the momentum of the aircraft from making it continue in a straight line out into space, because gravity's force is simply towards the centre of the earth, thus providing a downward component which would tend to make the aircraft rotate around the earth.
Q2. If gravity does contribute to the "horizontal" movement of the aircraft, how does it do that?
Q3. Would you agree that the "horizontal" movement is due mainly to the momentum of the aircraft, and secondarily to the movement of the atmosphere?
Q4. What degree do you have in physics, and when and where did you get it from?
Please number your answers accordingly for clarity.
I've done some web searches on this, and some were helpful, but I'm wanting specific answers to the above questions only from people with university degrees in physics, please.