A Lamp Of Negliligible Height Is Placed On The Ground ‘l1’ M Away From A Wall. A Man ‘l2’ M Tall Is Walking At A Speed Of  m/sec From The Lamp To The Nearest Point On The Well. When He Is Midway Between The Lamp And The Wall, The Rate Of Change In The Length Of His Shadow On The Wall Is  

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Question

A lamp of negliligible height is placed on the ground ‘l1’ m away from a wall. A man ‘l2’ m tall is walking at a speed of  m/sec from the lamp to the nearest point on the well. When he is midway between the lamp and the wall, the rate of change in the length of his shadow on the wall is

 

Solution

Correct option is

Let the man b at distance x from lamp length of shadows = h  

   

  

Differentiate wrt time  

                  

   

Testing

SIMILAR QUESTIONS

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Q9

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