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A point is moving on the principal axis of a concave mirror of focal length 24cm towards the mirror When it is at distance of 60cm from the mirror its velocity is 9cm/sec.what is the velocity of the image at that instant

7 years ago


Answers : (1)


1/f = 1/u + 1/v

f=24 cm , u=60 cm on substituting above gives

so, v = 40 cm

also :  1/u2.(du/dt) =  -1/v2.(dv/dt)

   1600*9 = -3600*dv/dt

velocity of image = 4 cm/sec towards mirror




7 years ago

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