all the way back to projectile motion... (1 Viewer)

[shkspeare]

hrmmz i was reading my excel book and it has the proofing behind why projectiles have a parabolic path

(click the attachment below)

now i dont understand why
delta y = (1/2)a_gt²

if that is the case they are taking u_y = 0...

i thought for a complete motion, we would take v_y = 0 and not u_y

thx...

 

[Constip8edSkunk]

im assuming the object is projected horizontally, hence, u_y=0. v_y would not be 0 as it is the verticaly velocity at the moment when the object strikes the ground, clearly not 0.

 

[zeropoint]

I'm not sure I understand your question. The fundamental equation governing projectile motion is

d²y/dt² = −g

Twice integrating gives

dy/dt = −gt + u_y

y = y₀ + u_yt − (1/2)gt²
Delta y = y − y₀

The above equation describes the vertical position of a particle projected from a height y₀ with initial vertical velocity u_y. For an object projected horizontally from a stationary elevated platfom the equation simplifies to

Delta y = −(1/2)gt²

Hope this helps.

 

[:: ck ::]

that isnt in the hsc syllabus is it 0.o

 

[abdooooo!!!]

Originally posted by :: ryan.cck ::
that isnt in the hsc syllabus is it 0.o

nothing beyond the 1+1 type of mathematics is in the syllabus... its hsc man

 

[KeypadSDM]

Originally posted by abdooooo!!!
nothing beyond the 1+1 type of mathematics is in the syllabus... its hsc man

They give you the formulas. Understanding them is HIGHLY overrated, just use 'em.

 

[...]

Originally posted by KeypadSDM
They give you the formulas. Understanding them is HIGHLY overrated, just use 'em.

exactly
the papers will not ask u to dervie or anything

otherwise there will be chaos

 

[abdooooo!!!]

Originally posted by ...
otherwise there will be chaos

i suspect this chaos comes from the incompetent science teachers not being able to do any sort of math apart from the actual calculation with calculators.

us students are superior

 

[...]

Originally posted by abdooooo!!!
i suspect this chaos comes from the incompetent science teachers not being able to do any sort of math apart from the actual calculation with calculators.

us students are superior

not my physics teacher, he is an animal..his maths is awesome...and yea, he always go off bout the syllabus and how he writes letter every yr to complain and nothing happened

 

[abdooooo!!!]

i wonder who came up with this idea of the new syllabus... the head of board of studies must be an english freak... first they make english compulsory, then they add three disguised english subjects known as hsc science.

 

[Xayma]

Originally posted by abdooooo!!!
i wonder who came up with this idea of the new syllabus... the head of board of studies must be an english freak... first they make english compulsory, then they add three disguised english subjects known as hsc science.

3... they disguised Engineering Science and shipped it off to another faculty and took all the hard maths out of it (though if they want they can still get difficult questions).

 

[lil_star]

@ KeypadSDM:....i wonder why they over rate the under standing!...as i did not properly understand projectile until i did it in 3u maths....going thru the process by integration/differentiation step by step, which makes it more logical and understandable...though its a bit hard at the beginning...but i guess not every physics student does 3u maths

 

[evilc]

yeah, i did all the physics trial / hsc projectile questions the 3u way...deriving the formulae

 

[Xayma]

Deriving them each time takes to long, just use them without understanding why thats the way.

 

[lil_star]

they cut marks in 3u maths if u dont show the derivation (see the 3u syllabus, it says u must know how to derive when asked)

even though deriving is time consuming...i find it easier to think thru.

 

[Xayma]

Yeah in 3U maths you do but not in physics. They have the formula sheet for you

 

[abdooooo!!!]

no there is more than one formula sheet.

 

[Xayma]

How many are there? 2. I know theres one with formulas and one with standard potentials etc.

 

[Constip8edSkunk]

1 sheet with constants 2 sheets of formulas 1 sheet for periodic table

 

[Calculon]

who gives a shit how many pages it is?