Projectile motion (1 Viewer)

[ash_s137]

Does anyone here actually know for sure if we are allowed to use calculus in solving projectile motion? Because I'm sure a lot of people do 3/4 unit maths and would have encountered projectile motion in those subjects, and it's done differently. I think the calculus approach makes more sense and it's the one I used in my school's trial, however I'm not sure if the markers in the HSC will allow it...

 

[L.B.U]

i dont think so. use da formulas they r easy enough..

 

[Jellymonsta]

if u get the right answer its all good. its probably safer to do it the physics way though...

 

[beava_69]

if u use calculus it should b ok, i used ohysics for 3u projectiles and i got the marks, so it should be the same in reverse

 

[Dan_the_man]

our teacher said we could use the 3 unit way

 

[kaseita]

It's fine, but its a waste of time, since you'll be mainly just plugging formulas.
for max height/range, your just rearranging the equations, so there's no real need to use calculus.

 

[Wintermute]

They shouldn't give you a projectile motion question hard enough to have to use anything other than those equations on the syllabus.

 

[Slammin' Sam]

Dont use 3 unit, it should be fine, but if it is a few marks worth you will not score the one for applying the correct formula, which is part of the syllabus.

Good luck everyone.

 

[Ronnie]

well the dot point in the syllabus says

Solve problems...........
using the 3 equations given,
so I think if you haven't studied them.... go and do it!

 

[superhubert]

then again, if you ONLY use those 3, there's no way you could answer most questions...

 

[Viator]

By far the easiest way to do projectile motion questions is by first principles.

v = u + at
s= ut + 1/2at^2
V^2 = U^2 + 2as

Just break up all the components and treat the vertical and horizontal components separately.

 

[spice girl]

It's a syllabus requirement to be able to solve all the problems they can throw at ya with the above 3 equations, btw...

 

[Dumbarse]

is anyone else gunna memorise the other equations
like the range, time and height ones??
cause ive done questions where theres no other way to do em other than these equations

u can do it maths way in physics,, but u are not supposed to do it physics way in maths.

 

[Ronnie]

Look as Galileo figured out.....

In order to work out projectile motions you have to break them up into vertical and horizontal components

vertical motions always have constant acceleration and horizontal motions always have constant velocity

this is where you plug in the 3 equations given in the syllabus... they don't want you to do it using 3U/4U maths way, I do 2U maths only so I wouldn't have a clue on what to do cos motion in 2U maths only cover up and down or right and left not both at once

 

[Slammin' Sam]

what are you a talking aobut...you can use physics in math, thats where they deerive the three and four unit formulas from...integration.

its quite simple to do it from first principles..

v=u+at

at peak of the vertical component final velocity is equal to zero

therefor 0=u-gt

gt=u

t=u/g

now u will get the initial velocity and just brake it down for the vertical component using pythagoras or what ever......y U=vsin

sub in the values and you get t

but this is only half the flight as the peak is midway, hence double the t value and then sub it into the formulas....

it keeps going like this...in math we were always taught by first principle and it has never failed me....why remember extra formulas when you dont need to

its illogical

i cant be bothered running throught he whole thing im still studying....ahhh four more days and its over