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1 Feb 2008 11:57:10 IST

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Rotating mirror

None

Figure shows a torch producing a straight line beam falling on a plane mirror at an angle 60deg..The reflected beam makes a spot on the screen along Y-axis.If at t=0,mirror starts rotating about the hinge A with an angular velocity w = 1degree per second clockwise.Find the speed of the spot on screen after time t=15sec.?

Info:This is from D.C.Pandey Optics & Modern Physics page no. 31 qn. no. 7

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GAURAV SHARMA

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Joined: 7 Aug 2007

Posts: 184

1 Feb 2008 16:05:55 IST

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consider angle PAO as a=30 degrees.

at any time t
a=2

t
then da/dt= 2

and y=3 tan a.

then calculate dy/dt

GAURAV SHARMA

Hot goIITian

Joined: 7 Aug 2007

Posts: 184

1 Feb 2008 16:08:11 IST

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consider angle PAO as a=30 degrees.

at any time t
a=2

t
then da/dt= 2

and y=3 tan a.

then calculate dy/dt

GAURAV SHARMA

Hot goIITian

Joined: 7 Aug 2007

Posts: 184

1 Feb 2008 16:08:41 IST

Like 0 people liked this

consider angle PAO as a=30 degrees.

at any time t
a=2

t
then da/dt= 2

and y=3 tan a.

then calculate dy/dt

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