Two plane mirrors of length L are separated by distance L and a man M2is standing at distance L from the connecting line of mirrors as shown in figure. A man M1is walking in a straight line at distance 2L parallel to mirrors at speed u, then man M2at O will be able to see image of M1for total time : a)b)c)d)Correct answer is option 'C'. Can you explain this answer?

Question

Two plane mirrors of length L are separated by distance L and a man M2is standing at distance L from the connecting line of mirrors as shown in figure. A man M1is walking in a straight line at distance 2L parallel to mirrors at speed u, then man M2at O will be able to see image of M1for total time :                    a)b)c)d)Correct answer is option 'C'. Can you explain this answer?

Answer

Solution

https://edurev.in/studytube/Solution/91d117ce-be67-4c18-909e-1ae4acaac7ec_t

Answer

The light from man M₁ hits the mirror and then reaches the man M₂. The positions of the moving man need to be found when the light from him hits the corners of the mirror to reach the standing man.
From geometry,
AO′=L/2+2(L/2)
=3L/2
Similarly, BO′=(3L/2)+2(3L/2)
=9L/2
Hence AB=(9L/2)-(3L/2)=3/2
Time taken to cover this distance=3L/u
Similarly time taken to cover CD=3L/u
Thus total time he is visible is 6L/u

Answer

The light from man M₁ hits the mirror and then reaches the man M₂. The positions of the moving man need to be found when the light from him hits the corners of the mirror to reach the standing man.
From geometry,
AO′=L/2+2(L/2)
=3L/2
Similarly, BO′=(3L/2)+2(3L/2)
=9L/2
Hence AB=(9L/2)-(3L/2)=3/2
Time taken to cover this distance=3L/u
Similarly time taken to cover CD=3L/u
Thus total time he is visible is 6L/u

Answer

The light from man M₁ hits the mirror and then reaches the man M₂. The positions of the moving man need to be found when the light from him hits the corners of the mirror to reach the standing man.
From geometry,
AO′=L/2+2(L/2)
=3L/2
Similarly, BO′=(3L/2)+2(3L/2)
=9L/2
Hence AB=(9L/2)-(3L/2)=3/2
Time taken to cover this distance=3L/u
Similarly time taken to cover CD=3L/u
Thus total time he is visible is 6L/u

Answer

The light from man M₁ hits the mirror and then reaches the man M₂. The positions of the moving man need to be found when the light from him hits the corners of the mirror to reach the standing man.
From geometry,
AO′=L/2+2(L/2)
=3L/2
Similarly, BO′=(3L/2)+2(3L/2)
=9L/2
Hence AB=(9L/2)-(3L/2)=3/2
Time taken to cover this distance=3L/u
Similarly time taken to cover CD=3L/u
Thus total time he is visible is 6L/u

Answer

The light from man M₁ hits the mirror and then reaches the man M₂. The positions of the moving man need to be found when the light from him hits the corners of the mirror to reach the standing man.
From geometry,
AO′=L/2+2(L/2)
=3L/2
Similarly, BO′=(3L/2)+2(3L/2)
=9L/2
Hence AB=(9L/2)-(3L/2)=3/2
Time taken to cover this distance=3L/u
Similarly time taken to cover CD=3L/u
Thus total time he is visible is 6L/u

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