projectile

[reza]

if we lunch a projectile with the act of air resistance which t (time) is longer
t1 =>from t=0 to arriving to the highest point
t2=> from highest point to the lanch point

[go quantum!]

You tell me. Choose two points at the same height of the trajectory. Compare their velocities. This should be a great hint.

[reza]

my problem is velocity i dont know how air rsistance affects on velocity?

[Office_Shredder]

Air resistance slows things down. That should be enough information

[perfectz]

If there is no air resistance(assumption), then?

[fffff]

Consider the forces when a particle is thrown upwards.
And the forces then it is going downeards.
Straightforward answer!

[DyslexicHobo]

In case you didn't know... Fair = -kv, where k is some constant. This means that the faster the ball is going, more air resistance is acting.

[reza]

then t1=t2? right?