Applied Maths Projectiles Help

oootrain

Hi.I am really stuck on the projectiles part in the Applied Maths course.

Can anybody please explain how to derive the formulas

u squared Sin squared alpha/2g


and


u squared Sin2alpha/g


Thanks

Nehpets

Is it from a question? What is the question?

The way I do projectiles is:

1) Draw picture, fill values in
2) Put in gravity - resolve if needed (sloped plane) (resolve in different colour)
3) Put down X values (u, a, Vx, Sx)
4) Put down Y values (u, a, Vy, Sy)

Then for pretty much all projectile questions you'll let Sy = 0. This is when the particle has hit the ground (the height is 0, obviously). It will give you t, the time.

For the range, just fill t (time) into Sx (the distance in the x direction)

JC 2K3

Neither of those are formulae, they're expressions.......

oootrain

its from question 18 in section 3.a of the fundamental Applied Maths textbook.

seinstein

I could help you with this, but by the time i'v etyped out the equations somebody else will have beaten me to it...but let me know if you still want the derivations because i saw them in an applied maths book by s.bostock and l.chandler i have. But do have a look at this:

http://en.wikipedia.org/wiki/Trajectory,

and this:

http://en.wikibooks.org/wiki/High_school_physics/Projectile_motion