mechanics ...doubt

dont know where i am making the mistake

but i am getting something like this

1+\tan(\theta +\phi)\tan(\phi)=0

8 Answers

49
Subhomoy Bakshi ·

θ = π/2 - φ2

49
Subhomoy Bakshi ·

instead of what u got i think u should get,

1-tan\left(\theta +\phi \right)tan\left( \phi\right) =0

dividing both sides by tan\left(\theta +\phi \right)+tan\left( \phi\right)

giving tan\left(\theta +2\phi \right)=tan(\pi /2)

thus the result

49
Subhomoy Bakshi ·

sorry i just flipped the theta and phi!! :-/

1
bindaas ·

my bad i did a silly mistake

it is

1+\tan(2(\theta + \phi))\tan\phi=0

shubomoys is wrong

1
bindaas ·

this leads to

2\theta +\phi =\frac{\pi}{2}

23
qwerty ·

i m getting
cos(2\theta +\phi )=0

23
qwerty ·

let
\hat{x},\hat{y}=unit vectors along the incline and perpendicular to the incline

\vec{g}=gsin\phi (x)-gsin\phi (y)

v_{x}=vcos(\theta +\phi )

v_{y}=vsin(\theta +\phi )

time of flight = t
t=2v_{y}/gcos(\phi ) =\frac{vsin(\theta +\phi )}{gcos(\phi )}

Range=R
R=v_{x}t+\frac{gsin(\phi) t^{2}}{2}

on rearranging R=\frac{2v^{2}sin(\theta +\phi)cos\theta }{gcos^{2}(\phi )}

\frac{dR}{d\theta }=0 ,\Rightarrow cos(2\theta +\phi )=0

23
qwerty ·

btw can u guys tell wat was ur approach ?

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