helpul Formula's not on the formula sheet...

[cameron_15]

What extra, useful formula's are going onto your cheat sheet?

I figure this could be a place where we share them. I know today a friend from another school showed me a formula for working out the angle of embankment for circular motion.

Angle of embankment = Tan^-1 (a/g) where a is centripetal acceleration and g is acceleration due to gravity.

I've only had to use this once but it saved a lot of time on a practice exam i did. I'll be making my cheat sheet in the next week so if i find (figure out!) anything else I'll post it up.

Surely there's more shortcuts out there!

thanks in advance

[/0]

is the horizontal distance an object travels when launched at the same height as it lands.

is a relationship between an object's kinetic energy and its momentum. It is just from the equations.

For an elastic collision, where kinetic energy and momentum are both conserved: ,
where are the initial speeds of the objects and are the final speeds.
This can be derived from the conservation equations if you do a little algebra.

[cameron_15]

Wow, thanks for those, they're great!

also, to find the center of mass of a system. m=mass and r=distance from point of measurement. Useful for torque type situations.

R (Center of Mass) = (m1r1 + m2r2  + m3r3. . + miri) / (m1  + m2 + m3. . + mi)

= (Σ miri) / (Σ mi)

just got asked to calculate this in a checkpoints question. Maybe old syllabus?.

[physics]

max height (projectile) =h= (u^2 sin ^2 angle) / 2g

[moekamo]

time of flight for symmetrical projection:
Ratio of two planets() masses and radius at the point between them where : see attached pic too

Alternate Voltage Divider Formula(instead of:) , just manipulated to get Resistances by themselves: also see pic

[kyzoo]

>.< Everything can be derived from first principles

[Blakhitman]

Yeah I'm not even gonna bother chucking them on cheat sheet.

I like working it out, which leads me to a question, if you used one of these shortcut-formulas and got the question wrong, would you get a mark for working out?

[kyzoo]

I just did a Physics prac exam and err...I conclude that you don't really need a formula sheet, as everything comes from the head.

[olly_s15]

I just did a Physics prac exam and err...I conclude that you don't really need a formula sheet, as everything comes from the head.

agree.

I'm basically filling my sheet with detailed study info for the sake of it. Motion and electronics comes naturally without any need of notes, for me, anyway.

[schnappy]

Except for the range equation for proj motion (as above), all the 'shortcuts' just confuse me anyway.

[cameron_15]

Yeah, I find that I never end up using formula sheets anyway. However, as a back up I will write out one.

The shortcuts could be used to check an answer. Not much point risking the loss of marks doing it any other way.

I guess I'll just have to stop being lazy