Projectile Motion- How to Calculate Displacement

[Jai]

Yes, since a bullet is being shot out of a gun.

 

[Nathanael]

Yes, since a bullet is being shot out of a gun.

If the velocity is zero, then it's not being shot out of a gun, it's just sitting in a gun.


When I said "initial velocity" in my other post I meant "initial velocity" after it's been shot

 

[Jai]

If the velocity is zero, then it's not being shot out of a gun, it's just sitting in a gun.

Yes, however I mean that for my original question, so now the approach may be different?

 

[NascentOxygen]

Thanks for the reply. Yes I did consider that and try using the equations t=s/v, V=u+at, S=ut+1/2at^2 and V^2=u^2+2as but none of these seemed to work. They are the only equations I have been taught involving time.

Those equations are good. They are what you use. You just need to apply them separately to the horizontal component of initial velocity and to the vertical component of initial velocity. Vertical motion is influenced by gravity, horizontal motion is influenced by only air resistance (if present).

If a projectile has no initial horizontal velocity component then its motion will just be a vertical rise, then fall back to where it started.

 

[Jai]

Those equations are good. They are what you use. You just need to apply them separately to the horizontal component of initial velocity and to the vertical component of initial velocity. Vertical motion is influenced by gravity, horizontal motion is influenced by only air resistance (if present).

If a projectile has no initial horizontal velocity component then its motion will just be a vertical rise, then fall back to where it started.

Thanks, I applied them separately and managed to get what I need. While you are here do you know some sort of formula that could be used to take into account air resistance? My teacher said that we need to mention the formula but not calculate it because it is too complicated to get the data for.

 

[NascentOxygen]

Air resistance isn't a constant retarding force, it varies as speed varies. http://formulas.tutorvista.com/physics/air-resistance-formula.html