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Rehaan_genius
Aug 11, 2008, 12:31 AM
Who can solve this?
I think its not a difficult one, only concept based, but I get stuck with it!

11002

Two inclined planes OA and OB having inclination 30degrees and 60degrees with the horizontal respectively intersect each other at O, as shown in the figure.
A particle is projected from point p with velocity u=10 under root 3 m/s along a direction perpendicular to plane OA. If the particle strikes plane OB perpendicular at Q (take g=10 m/s^2) then,
a) find time of flight from P to Q.(Ans:2sec)
b) The velocity with which the particle strikes the plane OB.(Ans:10m/s)
c) The height h of point P from the ground.(Ans:5m)
d) the distance PQ.(Ans:20m)

Rehaan_genius
Aug 11, 2008, 01:54 AM
actually what I did for the first part is:

I find the time when the initial velocity component becomes perpendicular to final velocity component which comes out to be u/gsin60=2 sec.
but remaining parts..? I have no clue..!

Rehaan_genius
Aug 11, 2008, 04:10 AM
I just want to know which thing can I use to solve the remaining parts. I want to try myself!

Rehaan_genius
Aug 13, 2008, 05:24 AM
Hey administrator! Help me! No one has solved it yet!

galactus
Aug 13, 2008, 05:38 AM
Wouldn't part b just be \frac{10}{\sqrt{3}}tan(60)

Rehaan_genius
Aug 13, 2008, 05:54 AM
Actually galactus! I don't get your hint!

Rehaan_genius
Aug 14, 2008, 04:30 AM
I got a hint which is;
just rotate the axes along AO and OB means now AO is y-axis and OB is x-axis, but I am still not able to solve it!

Rehaan_genius
Aug 15, 2008, 11:11 PM
Hi guys! I solved part a as follows;



11158
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11160

Rehaan_genius
Aug 15, 2008, 11:51 PM
And part c as follows;

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ISneezeFunny
Aug 16, 2008, 01:04 AM
Part b

As the hint says, rotate so that now AO becomes a tall building, and OB is the ground.

Now, you've got a "if I kick a ball horizontally off a building" problem.

You found out that AO is 10m

And the entire thing took 2 seconds.

... which, by my math, should hit at 20 m/s...

... am I missing something here? I haven't checked your math for prev parts... so I'm not entirely sure, but if you're getting the right answers...

Rehaan_genius
Aug 16, 2008, 02:32 AM
Part (b) is solved!

11164

And part (d) is also solved!

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