Question

Why time of ascent is more than time of descent when there is air resistance?

Answer 1

Aren't you sure it is not the other way round?

Answer 2

i guess it is right.. when we throw a particle air resistance continously slows down the particle's Hz velocity so the particle falls shorter than normal
during ascent it covers longer distance.. while in descent its Hz velocity which has already been decreaced .. decreased further so particle covers smaller distance in same time..

am i right.. ? more opinions required !!

Answer 3

Think in terms of mechanical energy.

Answer 4

it depends on the original muzzel velocity. If you launch at 10,000 m/s then the decline is at 9.8 m/s^2 So there is a negligable difference between launch and land velocity. Except some thing called 'nu' which is shape factor.

Answer 5

visocity right?

Answer 6

Frictional/air resistance forces are not conserved therefore lost on the way up. Therefore the half of the parabola on the way down is smaller.

Answer 7

What do you mean "smaller" ?
If body falls back to where it was launched from, of course distances travelled up and down are exactly the same.

Answer 8

My thinking Vincent is that: The kinetic energy is continually being reduced by the air resistence - so the potential energy at the top of the parabola does not equal the kinetic energy at the start; and since the air resistence continues on the way down even more kinetic energy is lost , therefore both sides of the parabola are not equal. I am off to the gym and will think about this while I run for two hours.

Answer 9

As energy is not conserved due to friction, at same altitude, velocity on the way up is greater than velocity on the way down.

So at each and every altitude, speed down is less than speed up, so the time taken down is greater than the time taken up.

Answer 10

But the distance down is less. I need to stop being lazy and actually use equations.

Answer 11

on the way up its de-acc. in vertical axis is g+(Friction+drag)'s on way down it is g-(Friction+drag)'s distances are same.. of course it has to be!!!
(Friction+drag)'s acc wont be constant it will depend on shape size material instantaneous velocity etc
acceleration and deceleration will be varying constantly. time for both half of path will be varying.. and there will be a deceleration in horizontal axis too stopping motion.
consider them all =D