1more logical...
A spotlight S rotates in a horizontal plane with a constant angular velocity of 0.1 rad/sec. The spot P of lights moves along a horizontal wall at a distance of 3m. The velocity of the spot P when A=45° is_______________________________m/s.
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5 Answers
1rotate kaise karra ??
seems its a nice question... but pls tell how is it rotating ??
or tell... from which chapter...
mine is ARCHIVE 2008... so its not pg.99 nymore :(
1from watever i understud of the question,,,
we need to work out with the projection of this PS .. right?
so, projection of SP = 3m (by geom..)
now vel = ωR .
here, R= 3m, ω=0.1
so is the ans 0.3 m/s ??
62well akash
the height SO is constant. I take O as the base from the point S
AO=SO tanθ
thus,
d(AO)/dt = SO sec2θ . dθ/dt
thus, v=3 x 2 x 0.1 = 0.6 m/s
is it correct?
3i faced a similar 1 in 1 of mah xams........only diff 60 instead of 45[3].........adopted nish bhiyyas method only......
actually in many situations like this , a rod placed between 2 perp walls etc u can use
sin , cos , tan or cot θ which ever contains a constant in thier terms....[like here 3m is the constant] .....is used and differentiated or double differentiated acc to wat is req........
